I know that mplayer has the ability to skip frames, which will result in faster playback (automatically even, I believe). Also, of course, it can scale a high resolution video down on the fly. I do believe in some way mplayer can do the things you describe, the only problem is that it probably takes CPU time to do so just like it does to convert a high quality movie down to a lower quality on any PC. I'm not sure how this TCPMP software would solve this problem, unless it takes advantage of some ARM hardware ability that helps the process.

As far as porting TCPMP, the challenge there would be that it's made for Windows. Which of course makes the port work a lot more difficult than most other apps ported to Maemo.

In the meantime, check out an mplayer man page and see if the functionality exists in there. Mplayer does a LOT.