To import and play D90 Movies ( big buzz about it, numerous users ). You have under windows to add an mjpeg codec, it's ok with Morgan or Mainconcept.
But I've tested on many PC config and the playback on the Timeline is very Bad (slow and freeze with 100% CPU even on dual Core 3Ghz RAM) on every Config. I 've read the same pb for other users on many forum.
So I've tested every MJPEG codec it is the same.
With low quality setting and Frame reduced to 15% it is the same !
In Quicktime or VLC the playback is good,
so HOW TO CHANGE THE DEFAUT PLAYER IN CS4 (there is a menu for that but I have only the choice of AdobeMediaPlayer !)
Vegas has added D90 support in the last edition, so I have tested and the playback is very fluent, even with a poor config(pentium m 1Gh ram)