If you can't figure out why this is dangerous, stay out of my shop.
You've probably seen things go wrong on a dyno before, unless YouTube is blocked where you live. Just the fact that you're trying to keep something in place which wants nothing more than to go, should tell you that things won't go smoothly. So if you happen to find you're having a hard time finding traction while dynoing you're awesomely overpowered trike, maybe don't get your buddies to all pile on.
Doing something like that could easily get a lot of people hurt, and very possibly killed, so when you watch the video, keep in mind how lucky these idiots are.