kaveman, agree QuicktimePro does nothing with Alpha Chanel...it is not on that level of masking, composting, etc. I LOVE the slider in P6 and it works okay for me. I can select any two renders and the scrubber moves back and forth with not the slightest hesitation. GREAT for (as you said) comparing tiny differences in render settings. I happened to have an intense vid card in my poser rig, stollen from my son's gaming computer! ::::: Opera :::::