I like to think that in the first clip the ramp is red with the blood of his fallen predecessors.
Also, 'unnecessary' pain? These all look like valuable learning exercises to me.

Solid gold. Half of these deserve to be independent submissions.
Especially 2:53.

My favorite was treadmill on stilts. Just the idea of it had me laughing before doom struck.

All my stars for the cameraman's reaction at 6:14.

5:29... those skaters were so unimpressed by the kid's tremendous pain. I don't think one of them even batted an eyelid as he came crashing down.

I'm just amazed that I had only seen one of these already

Half of these are already on here. Many a dupe, but I met a number of new friends today too, so 5.

lulz

the Opa-Opa! one reminded me of that exploding tricycle on South Park

Also, "I'MBLEEDINOUTTAMYFUCKINBALLSDUDE!!!"

The little kid.

"Daaaaaaugh!" :D *SMACKO!*

Most of that pain was very necessary.

The Three Stooges were ahead of their time.

Thank you, thank you, THANK YOU for whoever compiled these clips for not including any background music. Let the screams of the damned speak for themselves.

Lots of dupes, but many new ones!

Thanks for making me spit all over my screen a few times.

Slow-motion is humanity's greatest achievement.

Thank you! That was brilliant.

it's all about the slowed down girl-screams at 3:33

And the second-to-last clip.

pure gold

This clip is going on my media server tonight. Here's a copy for everyone in case youtube takes it down.
http://www.multiupload.com/39M4MUHZFQ

My only complaint is how after almost all of these the cameraman either stops the camera or starts shaking it all over the place. You need to give it a couple seconds at least, and zoom in on where you think the person might be leaking blood, then end it. Or keep rolling. Either way, it seems like they stopped the camera too soon. Five stars though for the fact that these people totally got what was coming to them. Most of these I mumbled, "This CAN'T end well."

I am pretty sure the one where that guy got hit by the cannon recoil was a death :(

Count the number of helmets and you will have the number of people I sort of felt bad for.

4:26-4:30

The look on her face.

A hundred billion stars.

Desperately needs a schadenfreude tag.

Is it bad that I don't feel their pain?

Stars for everything between 6:09 and 6:25. As for the rest, I had to look away a couple of times.
The one with the cannon was almost certainly a death. One of the first things they teach those Artillery guys is not to stand behind the damn thing.