I'll comment on them as I get to watching them :p - I've already seen the Rainbow Dash vs Starscream and the MLP physics presentation though (I recommend the latter- it's brilliant xD)

Thanks for the videos

That's really clever xD It look a little while to understand what was going on, but once I figured it out, it's very good :p

Oh, I'd forgotten about the Pinkie and the Brain one... That's one of my favourite pony videos. It's just too perfect.

And that "A pondering and verbose tale of delightful equines" video had me laughing far more than I should have. Whoever made that must have been really, really bored.

Fantastic! I think I would actually watch a Pinkie and Twilight spin-off series :p (what am I saying? of course I would!)