Far too much power (it should have been at idle in the non-existant hold off).
I agree it does look from the engine (the sound in the background is a helicopter so nothing to do with his power setting) like he has a bit of power on. But judging by the flare...which was there, but just too high, would suggest he was actually at or close to idle. With hardly any fuel in the tanks and any significant power a PA28 (Cherokee/Warrior at least, not the heavier ones) will just float and float even if you come in at 60-65 over the fence and is difficult to slam on like that.
With a long runway (no idea how long the runway was in this case...) it could be advantageous to keep power on though...would have given more control authority to keep the wing with the missing wheel off the ground.
Might also have been a idea to cut the engine once full contact with the runway had been made...just in case another wheel had collapsed and brought the prop into contact with the ground.
I don't think there is anything wrong with passing comment on these videos...no point in just saying "oh what a rubbish landing" but thinking about and illustrating what a pilot may have done better in an emergency situation is constructive to the forum and the general debate on here. One day someone might just remember something they read on PPRuNe...it might just improve their flying or help them out in a difficult spot.