That 1500 bet was not a beautiful move -- it was a donk move.
That AK fold was a terrible fold. Your friend cannot have 2-pair or set before the river. Otherwise he would have raised on flop/turn to protect his hand against the flush draw. The river bet represented a very polarized range that only includes missed draw, A8 (A8 most likely would check call on the river since it cannot stand against a raise), and 88. It was a pretty easy call for a 1/2 pot bet.