Hmm. Several things make me doubt the veracity of this vid.
First, as the child is walking up, he is holding his own bowling ball on the right side of his body. When he falls, the ball is on the left side of his body, and rolling freely. While he could have had his left fingers in the holes, it is doubtful that the ball would have released his fingers right when the ball hit the ground. If his fingers were in well enough that the ball didn't fall out immediately, it wouldn't roll out once it hit the ground.
Second, the child's feet flung forward. Such a fall, especially at a bowling alley, is usually the result of a slip, but the child was not yet at the alley itself, and the floors leading up to the alley aren't usually that slippery. Also, the fall happened too fast for the way he fell. Yes, he would have dropped fast, but he most likely would have collapsed straight down or fallen backward. He didn't fall back, his feet were thrown forward, while his head just dropped.
Thrid, I have found no evidence of a lawsuit of any kind, which I find rather suspicious. If a child had been brained by a moron like that, there would have been lots of legal reprecussions, even if the parents didn't press charges, as the bowling alley could not let such a thing slip by.