Sorry to read of your son's accident. Our thoughts are with him, you and your family.
This sounds like a great project and it's nice to see the number of people stepping up to help. I'm willing to throw my hat in the ring as well, although I don't know what I can offer that hasn't already been offered.
As for helmets and related safety, I live in a mecca for outdoor enthusiasts and extreme sports nuts (Colorado). Helmets are a way of life here, or at least most people do seem to wear them when they should. What's weird is this wasn't always so. I never wore a helmet doing anything as a kid, no one did. Well, OK, I did for motocross and contact sports where it was part of the uniform. For anything less than that, nothing. Mountain biking, skateboarding, skiing, etc.. Nope.
I'm not sure what changed, but I recall that through the mid to late '80s and ever since then, a constant droning on and on at school and the popular local media about helmets and safety. That wasn't what converted me to using helmets, I became a convert my freshman year of college. It was peer pressure that got me to wear one, funny how peer pressure can be a positive force at times. I did it just to appease other friends and a mountain bike / trail riding group I had started riding with around campus. I became a true helmet convert when after wearing one regularly for a couple months, I had a crash. Didn't seem like a bad crash at all, didn't even know I hit my head or what I had hit it on, but it was enough to split the outer shell of the helmet and break part of that off while putting a noticeable gouge into the hard foam within. It was a Trek bike helmet and at the time (maybe they still do) they would replace them for free if the helmets were ever in a crash and damaged. So I swapped it for a new one. Since then, I pretty much wear a helmet for most everything. I find that I like them -- especially for skiing and snowboarding, they're the best thing for your head. Not only do they protect, but a good helmet doesn't get too hot or cold and is nowhere near as itchy as a crappy ski hat (or as stupid looking, ha!).
Ever since my daughter was born, I was preparing for the battle with my kids about wearing helmets... Never had to. It's become an automatic way of life here and they gravitated to helmets right from the start. Sure there are still many people who don't wear them, but by and large most people do when they should when riding bikes or skateboards, etc.. around here these days.
I think paulherrin made a good point about keeping it real. I remember that while in school when we would see safety videos, there were two kinds. One was the overly-dramatized kind where everything was set up and had an overly fake feel to it. Kids mostly just thought it was stupid and had little interest. Mostly it was ineffective, possibly even counter-effective. The other kind of video was the documentary type where it was more personal and they would showcase someone who had lived to tell their tale of misfortune. They were more intimate and drew a better emotional response, but the connection was not there, or if it was, still very distant. The problem with the intimately personal account is most kids still view the world as if they're invincible. They see one poor soul that had a mishap and they feel sorry for him, but don't believe it can ever happen to them, no matter how many times someone tells them it could.
I'm not sure what the magic formula is, but I think this is where Michael has the opportunity to make such a project effective. He is the target demographic for his message. He is the one in the most effective position to communicate to his peers the importance of helmets and other protective gear. I agree with Jeff Whitehurst's comment above about the helmet for increased confidence and advanced progression. I truly believe that is how the helmets have caught on around here. Tony Hawk for sure, but local Shawn White and countless others who have impacted kids these days are wearing helmets. I think the worst way to approach it is with scare tactics and fear mongering, which is how helmets were pushed when I was a kid. That just turns kids away and sends the wrong message. Same with trying to promote them as being cool... If you want a product aimed at teenagers to fail on a catastrophic level, all you have to do is tell them it's cool.