Disclaimer: I know nothing about the game of rugby.
What I DO know is that this hit rattled the fillings in my mouth so I can't imagine what it actually felt like.
Here's a picture.
Now, here's the video. Pay close attention to the sound from the hit.
I love how the dude got up right after the hit and didn't seem to be overly phased by having his head (almost) knocked off.
That's rugby tough.
Also, his team got the try.