uploaded videos from my iphone 4 directly onto my mac via Image Capture. all the videos are perfect. transferred the videos to a jump drive and watched on a pc and they are stuttery. watched on 2 different pc's and got the same thing. watched the videos from the flash drive on my mac just to make sure it wasn't the flash drive, and everything is smooth. also a video i made with imovie on my phone plays perfectly on my mac, but is also stuttery my pc. quicktime on the PC's are up to date.