With the "Local video" button, i added 3 videos (attached) in the formats : webm, mp4, ogv

The webm works well, the mp4 one just has the sound (no image) and the ogv one is infinitely 'loading'

Note that I have no problem with ogv format when it is a 'shared video' and not a 'local video'. The mp4 has the same behavior (no video)