Samsung Chromebook Series 5 review: Performance | from TechRadar's expert reviews of Laptops and netbooksWe tested a variety of video file formats and were rather disappointed with the results. Out of the box, we managed to get .mov and .MP4 videos to work just fine, but more exotic formats like .wmv, .mkv and a basic DivX .AVI were not recognised by the OS.
Chromebook can play formats such as MP4, MOV and Mpeg/Mpg. AVI files are not supported by ChromeOS. ChromeOS is a web-oriented browser, as such, it doesn't work with legacy codecs.
H264 seems to be the best option for playing back video.