I have a cheap Samsung bd-e5300 player and when I play the MKV on it, there's definitely something fishy going on with the scaling, like for example the crawl has some serious aliasing, that just isn't there when I play it on my PC and I noticed this issue with other 720p files as well. It could be this issue you were talking about but I don't know, because it sounds like you are experiencing some kind of motion judder, which I don't seem to. Funny thing is though, that once I remuxed the same streams to BD in TS Muxer and burned it to disc and played it on the BD player, the issue seems to be gone.