I have never had a problem with quicktime, but today my friend uploaded some clips from his small toshiba camcorder, not sure what kind but it plugged straight to usb and i opened the files on my imac. But when I open them, I can hear the audio, but cant see the video and it says I need to download another component. But I am not sure what I need. not sure what info I should post to get an idea, but I would like to know what to look for.