The Video File Player is probably the most half-baked feature on Language Reactor. 
It only supports video formats that are natively supported by Chrome. You can use ‘handbrake’ software to transcode video files, but, hopefully we find a better solution. Videos are not uploaded anywhere (well, the subtitles are processed on our server), you can load in whatever you like. No duration limit. Performance is not great in videos with many subtitles, will fix.
Ok, first bug report from Nathan:
