God damn, that's not how you fold a burrito. I know Hekotat says that is what he was taught, but that's not how I was taught when I worked at Taco Bell (granted, I started there in '85).
I can't find a drawing of the correct way, because apparently it is a forgotten art, and I'm not even going to attempt to draw a Paint diagram, but I'll try to describe it using the picture above.
Right away, skip step 2 (as in, don't fold the bottom yet) and go to 3. Except at 3, fold the left part of the tortilla as far over as you can go while still keeping the fixins flat, not that half-assed fold they show. This should result in excess tortilla overlap on the right. Now sort of "scrunch" the excess overlap as if you were trying to fold it under the fixins, making the fixins sort of roll into a tube. Now fold the bottom part up, again using all of the excess tortilla, not that tiny little fold they show. Now just roll the "tube" you had before one more time over onto the remaining empty tortilla on the right, and voila, you have a perfectly rolled burrito that will not leak from the bottom at all. Hopefully that makes sense. I just ate from fucking Jimboy's today too, and had a tortilla I could have taken pictures of if I'd known. If I have to, I'll eat from Jimboy's again, purely for scientific reasons!
Obviously this doesn't work any better than other methods if you over-stuff the burrito. Nothing helps in those cases.