A TVOD system allows the user to pay only for the content to be viewed. It is often compared to the video stores that were so popular years ago, where customers paid only for the movies they wanted to watch, without actually owning them physically in many cases.
Transactional Video on Demand can offer limited access to the content for the user who pays the established amounts, or it can be available during the broadcast of a live event, such as a soccer game, the Superbowl or a UFC fight.
The main feature of this system is that the user does not have to pay a monthly or annual subscription, but only pays for what he/she wants to watch. For example, if several months go by without any interesting content being presented for a given user, he/she will not have to make any payment on the platform.
Platforms that use TVOD usually work through the Pay Per View (PPV) system. Amazon uses TVOD on its Instant Video platform, as does iTunes when offering its content.