actually, the floor had nothing to o with it. If you noticed, the rungs on the ladder appear to be extremely narrow (top down) and tus provide very little traction for his shoes. As he was wiping at the window frame or whatever, he raised his one foot slightly (and hence causing all of his weight to rest on one foot alone) and the other foot didn't have enough surface contact with the ladder rung to stay where it was. As his foot began to slip off the rung, he pulled his leg up and put his right foot back down quickly. When he did that, the ladder moved ever so slightly in a right-left motion (that wouldn't not have caused him to fall had he not been off balance) that caused his already out of place center of balance to be thrown backwards. As he falls his head curled towards his chest and his foot pulled free of the rung from which it had almost slipped from. He hit the ground on his right middle shoulderblade and the rest of his body hit after that.
Had the ladder been made with less of a "space saving design" and more though put into practical application, this probably would not have happened.
/rant