I don't know if you are looking to spend any money, but you can could always get QuickTime Pro, which lets you save movies to your hard drive. It costs $30 though.
I wish there was a way to capture streaming quicktime. I do it the brute force way. I hook up my iBook's video out to a analog to DV converter to my G5. Then I use iMovie to record the full screen video coming from the iBook. Then I compress the movie using Sorenson Video 3 Pro and Cleaner 6 for the highest quality video with small file sizes. Videos look as good as the original when I am finished. It is the only way to save the keynotes for example. It is a major pain both in time and hardware but it works.
Right. The easy way to tell if QT Pro will fix your problem is to check if the playback bar fills in as the movie downloads. If it does, and you are able to instantly seek to any position in the filled-in area of the bar, the data is being downloaded and saved to your drive somewhere. If there's no filling-in action, and it takes a few seconds to rebuffer whenever you seek to a different position in the stream, then QT is getting the data on-the-fly and not saving a copy. That means you have to call BornAgainMac and contract him out for his (amusing, but still very cool) brute force method 😛
Edit: omg. two years later and finally I'm not a newbie anymore.
Using the DV capture method, I can also convert any full screen video format on the planet. This includes the popular Realplayer videos or Microsoft's Media 9 to Quicktime. Quicktime rocks!
Look into Snapz Pro X 2.0 it's only $20 to upgrade to from the bundle version and it can capture full screen video at 30fps flawlessly and encode it into any QuickTime format.