Playback in program monitor is tiling the clip hundreds of times, playing artifacts, and turning green.

​@erabbide It’s good you saw the difference with your buddies computer. You might want to try a brand new project. When I first tried your project I saw the same thing (in Windows). Then I created a new project, imported your clips and it worked fine in  26.5 b15, and in the shipping version 26.2.2. When I get to my main computer, I’ll try it with the most recent Beta build.

I’m a PC guy only, so on a PC, with that kind of error the first thing we’d recommend is to update your video drive. I’m not sure how that works on Mac (which I can see on the screenshot) but, maybe it will give you an idea. You’ll probably want to give us some info on your hardware. As for uploading a clip, I’d be happy to take a look, if you have a short one you can place on Google drive or the like...