Emirate's ICE entertainment system claims to be able to play files from an external media source. Which file types and media formats does it recognise?
Potentially this could vary depending on the exact version of the software, however on every Emirates flight I've ever been on that had this feature, as well as every other airline that has had this feature, the only options were to display images (JPG, GIF, and possibly others), music files (MP3), and on at least some systems, PDF files.
No system I have ever found has had the ability to play video files from external media.
Panasonic did release a system many years ago for displaying video from an external source on their inflight entertainment system, however this was very poorly adopted - the only place I've seen it is on a very small number of United Airlines planes (mainly the 747's which have now been decommissioned), and even then only in Business/First class. Even then you required a special cable to use it, and the video was actually being generated by your device, with the entertainment system basically being used as an external display.