Hmm - shows promise but it's got a way to go yet before it becomes any sort of "magic bullet", and that's before anyone starts taking serious countermeasures.
Drone:
It took ages to bring the drone down, so:
a) How much longer would it take if the drone had an ablative or reflective coating to reduce the heating effect of the laser?
b) How much longer would it take if the drone had a laser sensor that told it it was under attack, prompting it to take violent evasive maneuvers? Remember, it doesn't have to stay permanently out of the beam, it just has to change aspect so that the heating is distributed across the airframe and hot spots get a chance to cool down.
Mortar Rounds:
It took roughly 10 seconds to destroy each mortar round, so:
a) How hard would it be to swamp the laser with mortar bombs or multiple rockets, so that it couldn't get them all before they started landing on it?
b) How much longer would it take to destroy each round if they had an ablative or reflective coating to reduce the heating effect of the laser?
c) The laser was engaging the rounds from off-axis, giving it a clear, side-on view of them from just after launch. What would happen if they were coming at the laser (so smaller target profile) and from behind a hill, so the laser didn't get line-of sight until halfway through the flight?