Man...should have got myself a Full HD plasma

Anyway...I read through the Madhat review....what does the guy mean by:

"Next, I tried a 1080p x264 file, also in an MKV container, this time with DTS audio. The video bitrate was around 15mbps, and I honestly expected many dropped frames. However, I was proven wrong, as the file played back with no issues at all.

Then he said

I tried playing an MKV file containing MPEG2 video and AC3 audio, and it did not play. While that’s not a traditional container for those codecs, it still should have played."

Can someone enlighten me...AI'm still new to this HD stuff..