I watched the video. This is the exact form i've espoused for years-well behind the head instead of to the face. I've always said that extensions are the no. 1 mass builder of all exercises for tris, as they both say.
I don't agree about the EZ bar, grips other than a straight bar are better for most people not only because they're a lot more comfortable but also because shorter bars are easier to balance. Some guys even use an EZ bar for close-grips for the same reason.
The best of all of those IMO that anyone should try (i'll bet he never has) is to use either a hammer grip bar or 2 hands around the end of a DB, which virtually no one does and is not only more comfortable but easier to balance. However some can use the straight bar without it hurting the wrists, especially if a wider grip's used as seen there, which also feels slightly different on the tris. The other guy doesn't do extensions, mainly because he says it hurts the shoulders not because they're not good. Skulls like he's doing hit the elbows and tris closer to the elbows far more IMO.