Hi Alex. I've just tested it, and am able to reproduce the problem. It's only occuring for me when I set the target for the image overlay to Left or Right (so if you set it to Output, then the problem won't occur) and have a video that doesn't cover the entire area that the image overlay is set to. I've made a note to look into fixing it, and shouldn't be hard to fix for 1.5.1 or 1.6. Thanks for letting us know about this.