The solution is unbelievably simple - put this as one of your video tags: yt:stretch=16:9 Note that you can include any other tags that is related to your parody (e.g. "hitler rants parodies", etc.) A less common case is when the aspect ratio of the clips is preserved, but the resulting video is in 4:3 aspect ratio with letterboxing above and below the clip. In this case, put this into the tag field instead: yt:crop=16:9 A very important note is that you absolutely cannot do this if any part of your subtitle is in the bottom letterbox, either incidentally or intentionally.