From your first link:
Statistical evidence suggests the use of helmets may in fact enhance the government's invasive abilities. We speculate that the government may in fact have started the helmet craze for this reason.
So it was the goverment all along. Brothers and sisters take your tin foil hats. It was all a lie.
Except that the last line of "We speculate that the government may in fact have started the helmet craze for this reason" is sarcasm.
I prefer the last study since it actually give us a demonstration of the blocking power of my shiny friend.
I would hardly call a YouTube video a "study" on this subject.
Furthermore, you can still read the results of the first link you posted, so there's no reason to "prefer" one over the other - except that the first link you posted was much more rigorous than that short YouTube video. It also has the advantage of being conducted by MIT inhabitants
I have no idea why I'm spending my time on a subject as absurd as this... -.-