I'm trying to play some .m2ts files. I can see the video, but I have no audio.
Most probably, the problem is caused by absence of AC3 decoder in your system. Current version of MPEG player doesn't comprise AC3 decoder, but we're going to release the new version of MPEG Player with AC3 sound supported in a couple of month. In order to avoid any problems with audio we would advise you to install some third party AC3 decoder (free version of this codec is available here: http://ac3filter.net/).