Don't know if you got it fixed but that's from the auto decompressioner on the opposite side of the cam from the timing chain gear. it has a rocker arm that opens the exhaust valve i little to lower compression and that clearance is out of adjustment
You'd think with two people the camera work would be incredible, but its not nearly as good as vids I've watched with one. Plus, I've quit @ 1:34 and learned nothing.. You mean well I'm sure, I just don't see any useful instruction.