Seems you've done it. The web players aren't working for me but the ZIP did the trick. Seems there's two 'Jam' samples that are slightly different from each other. I won't deny that does seem to be the same as from the actual song, though if not for the actual 'Jam' on it, it's just an orchestra hit (one with a break of sorts), which was very popular from the late 80s into early 90's. And yeah, it does seem like we have some beatboxing on there that could very be MJ, if the story about the tape is true. It does seem like all the puzzle pieces are here, but as ever I'm not convinced MJ personally had much to do with what we got in the final game.