I once saw a Youtube video with an old man’s face embedded in the background, in about one frame. I don’t know how I picked up on it, but I did. None of the other comments referred to it, and the owners of the video never explained to me what it was for. (It was a comedy video, so not sure…)
That was only frame from what I could tell, and it took a lot of tries to get the Youtube player to stop on it!
The opacity was turned down some, from what I remember. Very similar to the faces in The Exorcist.
Now, for yours, first I’d recommend having a friend watch it, and don’t let him in on the joke until after he sees it. Ask him to watch 15 seconds before and 15 seconds after and see if it’s noticed. Flat out ask him afterwards. Like you said, YOU know it’s coming so maybe it’s just you. This way you’ll know.
Beyond that, try putting it in a spot where the action or some item on the screen blends it and makes it less noticeable. A splashing wave, a quick move of the camera, someone throwing a football–scenes like that provide an opportunity to tuck your burger in there.
The only other suggestion I have is perhaps you can play with the color or levels, etc., and get that burger to blend in a bit more.
