Which version of the program are you using and on what operating system?
Have you ensured you have the latest version of Quicktime, per the program's requirements?
What model of camcorder is this video coming from and what resolution is it?
Codec & Format information, with 2 links inside to read
-read both links in reply #1 http://forums.adobe.com/thread/1270588
Report back with the codec details of your file, use the programs below... A screen shot works well to SHOW people what you are doing
The Help-and-Tutorials page http://forums.adobe.com/thread/1275830 may help