hedwards: I dunno, I can't view the video as I don't have an account. And I don't think that you can create an account without it being a G+ account.
adambiser: I didn't realize that there's no way to view "age restricted" videos there without an account.
It's the same one as
this one. Yeah, I was surprised by that as well. Of course if this isn't the video, I'm probably going to have a hell of a time trying to find the right one as video searches are still pretty much impossible and I saw the video several years ago.
EDIT: The section starts at about 9:41 and I see that it's somewhat less clear than I recall as to what about that was intended and what was unintended. It doesn't sound to me like it was intended for people to be able to glide across the walls and the code to do that predates the code that made doing so beneficial to the player.
I definitely can concede that your interpretation is reasonable though.