PS3 has slightly less memory available in game than 360. Though both ship with the same amount of memory (512 MB), the XMB eats up a little bit more than the 360 blade stuff. Since all PS3's are also guaranteed to have a hard drive (unlike 360), we stream the replay data straight to the PS3 hard drive as the play is being run instead of streaming it to memory (like we do on 360). Unfortunately, writing 60 frames per second to the hard drive in realtime is a performance hit and will end up causing hitching and gameplay framerate loss, so sometimes we have to skip a frame or two (depending on what is happening on screen and how long the replay is) to ensure we don't screw up the normal gameplay experience. Since the replay buffer on the hard drive now has less frames, it has less fidelity when you play it back.