The studios are restricting the number of titles available for VOD for fear of programming being copied, as well as a perceived lack of profit. Movie studios generally won't allow movies to be available through VOD until 45 days after the DVDs go on sale. At the time of this writing (spring, 2006,) studios typically earn only $1 or $2 from each movie rental but can make $12 or more from each DVD sale.

VOD advertising is often sold on a cost-per-impression basis. The problem with doing business based on impressions is that programmers arrive at the count in different ways. An impression could mean an ad has been viewed in its entirety or only in part.

TV-based Video on Demand is often available in these formats:
1) Free VOD, which includes Basic or Family Packages.
2) Subscription VOD, where a separate regularly re-occurring fee is charged for a plurality of VOD programming. (Examples are Showtime On Demand and HBO On Demand). 
3) Pay-per-view VOD, (Transactional VOD), often used to deliver individualized programs on demand. With PPV VOD, often the customer can watch all he/she wants in a 24 hour period. Special boxing matches are an example.

Typically each of the above operates the same. Each offers play, pause, stop, fast-forward, rewind, etc.

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Interactive Video on Demand - (IVOD) - This is the standard type of TV-based VOD today (though it wasn't when this dictionary was first written.) VCR, DVD and DVR type functions, such as fast forward, rewind, and pause are offered. An IVOD system can have three components: (1) the user's "set-top box", or equivalent (and it's components,) (2) the network it's connected to, (and it's distribution components) and the (3) servers with archives of programming.  Typically the subscriber's set-top boxes are how they communicate with the VOD servers. The interactive functions that the VOD user has at their disposal can include:

1. Play/Resume  - Start a program/movie from the beginning or resume after temporarily stopping the show.
2. Stop - Temporarily or permanently stop the presentation of the show.
3. Pause - Freeze the picture.
4. Jump forward  - Jump to a particular time in the presentation (movie) in a forward direction.
5. Jump backward - Jump to a particular time in the presentation (movie) in a backward direction.
6. Fast Forward (FF)  - Browse through the movie in the forward direction with picture and sound on.
7. Slow Down - Going forward at a lower rate than normal but with picture and sound.
8. Reverse - Playing the movie in the reversed direction with picture and sound.
9. Fast Reverse - Browse the presentation in the backward direction with picture and sound at a faster speed than standard reverse.
10. Slow Reverse: Go backward at a slower speed, with picture and sound.
11. Other interactive features include the ability to avoid or select advertisements, to investigate additional details about news events and to browse, select, and purchase goods.

True Video On Demand - (TVOD) - (Now just known as Video on Demand) - An older antiquated term for video on demand (VOD) service where individual users would get immediate responses when interacting with the VOD system. With TVOD, the user could order the program at will and be able to do any VCR-like commands on the VOD system with the same quick response time as when working a VCR. This increased speed of the response time can significantly increase the cost of operating the VOD system. An alternative is Near Video on Demand (NVOD) as it reduces the cost by increasing the waiting time. TVOD is more often just known as VOD (Video on Demand) as it is the standard form of VOD in television.

Near Video On Demand - (NVOD) - A particular program/movie is advertised to start a regular intervals over a particular channel.  You pay your money electronically and select what time and day you want to start watching the program/movie. A small portion of the program/movie may be sent and stored on your DVR/set top box buffer or hard drive, most of the program/movie is viewed from (off of) the server of the network operator offering the NVOD service. 
    Typically you can fast forward, rewind, pause, etc. with NVOD as you're able to do with TVOD. http://etvcookbook.org/glossary/nvod.html

Subscription Video on Demand - (SVOD) - (Subscription-based Movies and/or Programming) - Generally movie/programming packages are scheduled events; SVOD can make it possible, for a fixed fee, for subscribers to have unlimited access to movies/programming during a specific time period, such as a month. The opposite would be Free Video on Demand (FVOD) where a subscriber pays no special fee for the programming.

Free Video on Demand - (FVOD) -  (a.k.a. Free On-demand, FOD, FVOD, Free Video on Demand) – Video on Demand programming that a network operator makes available as part of a basic content package. FOD (FVOD) can make it possible for subscribers to have unlimited access to movies/programming offered during that time period. The opposite would be Subscriber Video on Demand (SVOD) where a subscriber pays a standard reoccurring fee for programming that may have no, or limited advertisements.

Quasi Video on Demand - (QVOD) - Same as Near Video on Demand except that the show (programming) only will be presented if a minimum number of subscribers sign up for it.

Impulse Video on Demand – (Impulse VOD) - Though now-a-days it's typically all just referred to as "Video on Demand" but in the past, this term often referred to the ability to order TV-based Video on Demand programming, without having to first phone in your order to the network operator.

Exclusive Video on Demand - (EVOD) - When a particular TV-based VOD content provider (most likely your network operator) offers a function, service and/or program that no other content provider has (or very few have), it might be called Exclusive Video on Demand.

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   Two major types of VOD are streaming video and non-streaming video. Streaming video (sometimes known as HTTP Streaming video or Progressive Download) is when the video  is compressed and sent over a network, such as the Internet.  It’s then decompressed by the receiver (set-top box) for displaying on your screen. Typically the file begins displaying before it has completely been delivered to your set-top box (to save transmission time and bandwidth.)  Literally the programming plays as it's being downloaded.  The non-streaming variety of video needs the downloaded files to be completely sent before they can be played.
   Important also are the system’s video servers. Video servers are a computer system capable of storing large quantities of video and serving it (sending it) to user's TV systems. Also important is the Conditional Access System. Conditional Access is an encryption/decryption management method (security system) where the broadcaster controls the subscriber's access to digital and Interactive TV services.  This can ensure that the person is who he/she says they are (authenticity) and provides security for purchasing and other transactions.  The end-users (subscribers) have a receiver (set-top box) that allows him or her "Conditional Access" to the services available through that service.  "Smart cards” (or the equivalent) may be used to access the system by the end-user.

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   TV-based Video on Demand is revolutionizing the television viewing experience. Why? Because in time you'll be able to view most of your favorite programming (shows) in this manner, and not just movies and/or special events. Imagine at any time of the day or night, searching interactively through your TV and finding your favorite sit-coms listed by episode. Click interactively on an episode’s electronic button, in the same manner that you would on a Web page and up comes what that episode is about and other pertinent information about it. Want to watch 10 episodes in a row of that sit-com, even if it’s midnight? No problem, you make your own viewing schedule with Video on Demand. (Chances are good you'll need a digital TV package).
    One of the major reasons for implementation of VOD is to cut down on “Churn.” Churn denotes subscribers that start and stop their subscription faster than the network would prefer, a process that adds to the business cost of networks. The assumption is that if more options are available for the customer, they will be less likely to stop receiving the service.
  Developments such as improvements in VOD servers, better codecs, better ethernet, and Passive Optical Networks (PON) etc. technologies replacing the older, slower technologies such as asynchronous serial interface (ASIs) connections, have been essential.

Microsoft’s US-based Video Marketplace, which launched in November of 2006, as of mid-2007, has around 2,100 hours of movie downloads available to Xbox 360 owners. It's introduction to Europe is set for August, 2007. (Of course we all know about iTunes' success as a download service.)

Various Other Related Terms