It might not be as deadly as a car, but hitting somebody with your bicycle is still very dangerous, especially if the victim is already in a compromised position.
The man in the video was crouching down while working on an E60 BMW 5-Series, completely unaware there was an out of control cyclist heading his way.
The fact that he had his head all the way inside the wheel well seems to have resulted in some type of head injury, although it's hard to assess if there was anything wrong with him afterwards.
He immediately started cursing out the cyclist, so be mindful of the language while playing this video.
On one hand, we can certainly understand his anger. Suddenly banging your head on your own car can't be pleasant, especially when someone else is to blame and you're still in somewhat of a shock. Then again, obscene language and violence (he later took his frustration out on the bicycle) aren't appropriate either.
Do note that some people are suggesting this incident was staged, which is a possibility. We'd actually prefer it if it was genuine though, and the guy on the bike didn't crash into that man on purpose.