Although MKV isn't on the official list of supported formats, many users stream it everyday without problems. I've streamed a 20-30GB Blu-ray movie at home, but only some devices and networks can handle these types of files. For the best results you'll need a Gigabyte Ethernet network and a server with a fast CPU and disk. Also, some devices have problems buffering files with data rates that high. For example, on our Samsung TV, it takes a minute or two for the video to get relatively smooth playback rates.