FFMPEG is a server-side application that compresses and encodes video as it is uploaded. If you have ever used a Youtube or Google Videos you will notice that you do not have to worry about compressing or encoding your video before uploading it because FFMPEG is used to compress your video and encode it to preset specifications when you upload it.
FFMPEG is not offered on LexiConn servers. As you might imagine it takes an enormous amount of processing power and memory to compress video. Running an application such as FFMPEG in a shared-server environment would have a noticable impact on server performance for all users.