Hi, Cutting my movie I faced some strange puzzling behavior to which I couldn't find any explanation (otherwise wouldn't come here): some transitions fail playing back unless you move the handler back and forth manually. I made a screen capture, see the embedded Youtube video: its first part is me moving the playback handler manually followed by an automatic playback. I must add the transition is acting nicely in other places on the timeline, and the clips are created of whole original videos, not split etc. In the case of automatic playing back the transition in trouble is skipped as if not being there at all. Why? The link: Update. I created a test project with just the two clips having that transition in-between. I noticed that when I'm trying to play the second clip Preview screen is absolutely black. The Source file (MP4) is playable in QTP X smoothly.