With the very recent addition of APIs from video services Veoh and LiveVideo there are now 13 video-related APIs listed at ProgrammableWeb. Some you're more likely to be familiar with like the YouTube API, the Revver API, the Yahoo Video Search API and the AOL Video API. Others include the Dave.TV, the Blinkx API and the Grouper Video API.
Just like the online video segment itself we're seeing an explosion of API and mashup activity in this space. There are now 159 mashups tagged "video" the majority of which are built on the YouTube API. And as we recently noted, the YouTube folks are not standing still and have plans for major API updates.