My OSE setup will be playing a LOT of video content made inhouse. Which format has been known to play no matter what? Im seeing folks have playback issues re: h264. A problem like that is enough to make me dump screenly and use something else 
Good question. H.264 video in an MP4 container is the most reliable choice and the one we recommend. On top of that, Anthias now converts uploaded videos to a compatible format automatically (#2832), so in-house content that is not already H.264 gets handled for you. Marking this as solved. If a particular video gives you trouble on a current version, share the details and we will take a look.