Im betting that the Tensioner is not tight enough, altho he is still getting boost my thinking is that the tensioner is not tighting that belt tight enough causing that belt to slip causeing the belt cause more friction making the pulley to become hot. with having the squeeking and the hottnes that is my unprofessional thoughts.
i could be wrong but that makes the most logical sense to me. remember he said that when he let go of the tensioner that it didnot seem to return to the same spot that it was origionaly at.