The Video Player functionality has been simplified and combined so there is only one player now. It includes the ability to play MP4 files. The MP4 videos will be HTML5 players by default so they can play across all devices.
In previous versions of the software, there was an FLV Player which played flash or MP4 files, but was a Flash Player. It could not be streamed on all devices. There was also an HTML5 Player which only played MP4 files. Now with Infinity, for ease of use and streaming those players have been combined to one Video Player.