I thought that Quicktime could play mp4 h.264 encoded movies.

I normally have perian installed, and the movie plays fine - very smooth, good quality. But when I disable perian, quicktime plays the movie very choppy with a lot of green off colouring.

Inspecting the movie file says that the format of the file is: Apple MPEG4 Decompressor, 528 x 368, Millions.