The reason Canola plays videos from Nokia's ITVC choppily is that Maemo's mplayer is optimised for DivX/Xvid-style videos, rather than the MP4 that ITVC outputs. If you have mplayer installed, Canola uses it by default. A search of the forum will show how to get it to use the built in framework rather than mplayer.

The built-in Media Player isn't as optimised, but plays both transcoded DivX and MP4 files perfectly well. It's certainly much improved over its OS 2005 cousin.

In lieu of optimisations for MP4 in mplayer, more intelligence in the funky front-ends like Canola and MediaBox on which playback engine to use based on a given file's type would be wonderful.