Hello! I am trying to insert a video inside a mock up of a phone but once I insert it on the preview on certain areas of the screen it gets this glitch effect and also green flickers for no apparent reason..
Sorry for the preview glitch in After Effects. We'd love to help you out but we'd need more information so that we know what are we working with.
Would you mind sharing your system specifications (CPU, GPU, RAM, OS) and details of the footage you are working with (frame rate, frame size, format/codec)? Is it happening with all the media files? Also, please check if it is happening in the exported file as well.