@ Lauris: I did a test with a 1080p-file and everything was fine, although I just watched two minutes, but I also had tested a 1:1 copy of my Blu-ray via an usb-drive (just put it into a Mp4-container), and it played it nearly perfectly on my tv.
downloaded this app, its big > 350mb, but my favourite app so far. streamed mkv file ripped from band of brothers buuray stored on a nas perfectly
It seems that this app cannot support mkv's with DTS, only AC3. And so far no .srt support either.