Example tutorial here (but not for iMovie) You can sometimes reduce the visibility of the flicker by duplicating the video track, moving it forward by one frame, setting the upper track to be semi-transparent, and see if this helps. But even if you have a matched frame rate you will still get flicker because the camera and projector's clocks are not synchronised - so one will be in the process of closing a frame when the other is still recording a frame, hence the flicker. Most video recorders run at 25, 29.97 or 30fps. If it's a film projector it might be running at 24fps. The flicker usually comes from a mismatch between the camera recording the footage and the projector projecting it. It would help a lot if you provided a sample showing the problem. Hope this helps you or anyone else using a search engine to love their quirky issues like i did to find the original post. I got a bit carried away and made an example video. It's a very satisfactory result.Д¬aveat: If anything crosses the projected image is will look like it has a strobe effect and any animations, video or transitions will have this also, however for a set of static slides you should be fine. I also reduced the brightness on the base layer by 100% (referring to Lumetri Scopes and using my eye to avoid blowing out the slide image). Working in Premiere Pro, I layered the video 3 times, cropped each layer to the projection screen area, reduced each layer to 25% opacity and advanced each layer 1 frame on from the last. I've just had the same problem with a single chip DLP projector image in shot with the banding looping over about 5 frames. Tomh's advice to double stack the video layer, reduce opacity by 50% and advance a frame is a great starting point and certainly works well on fluorescent light flicker.

Flicker premiere pro