What model of camcorder is your video coming from and what format and resolution is it?
When you open your video in the free download Media Info, what does it list as the resolution, frame rate and audio and video codec?
BTW, I highly recommend against installing additional codec packs on your computer. These codec packs can overwrite your existing codecs and really bug things up.
The only thing you need to install besides the program itself is Quicktime, per the program's system requirements.