the explosions at the end were armor company artillery from the US player. Not an exploit of the B4 bug.
That being said, Luvnest DID use the b4 bug twice immediately after building it. He scored two kills vs infantry with one of the shots, and did a bunch of damage to a panther with the other. So, not really that big of an impact on the game.
Still, don't do that Luvnest

.