#1 - I really don't like to see homemade pieces of metal spinning at 10,000 rpm
#2 - Seems like if the angle was locked to the correct one for a twist drill it would be sweet. But if it pivots your angle is variable. Maybe that isn't a big deal?
#3 - I'd put a beefier support post on it but it looks like a nice one
#4 - When he turned it on and the chuck started wobbling I figured it would break right off at that point. I'm thinking that one is pretty risky unless the chuck is designed for the application.
#5 - Pretty cool edge guide
#6 - See #1
#7 - Nice makeshift wrench if you lose the one that comes with it or if you have multiple sizes of grinder nuts to tighten (Joel, I think this is the one you didn't see)
#8 - I like this the best and it does a better job than #3
#9 - I think he'd be better off clamping the metal in the vise and sanding by hand. The sanding disk isn't flat so he can't get the full face of the square stock sanded while it's flat on the table. And using it to cut through metal is risky as you could see it nip the metal and drag it through at the 16:43 mark
#10 - See #1
Just my opinions but I agree, common tools can replace some of these riskier attachments.