if they were randomly placed, then couldnt you have a sponsor-block type system where instead of the ad segments being marked and skipped, information about the video is externally stored somewhere (like perhaps a really low res screenshot of the video every couple seconds, or some number generated algorithmically by a frame of video), and the results should be the same for all users for the actual video part, but if the ads are placed randomly, the ad section will suddenly not match the data other users had, prompting the video to skip until it matches again (with a buffer included if they remove the ability to move forward)