Acoording to the Plex tv code , MKV with the following video and audio encoding is natively supported by Plex. This means if your MKV is encoded with the above video and audio codec, it should be able to direct play on Plex. In December 2009, the US-based Plex, Inc. was founded with Ullman as CEO and Feingold as CTO. At that time, Plex had 130 apps, the most popular of which were viewers for Apple Movies Trailers, YouTube, Hulu, Netflix, MTV Music Videos, BBC iPlayer, and Vimeo.