Nice vids *mm* .. Good Luck with the shoot as well.
IMO you are solid with the form & pulling with your abs, NOT your neck & arms, even though it looks that way just slightly... MAYBE a little with your legs, but that will happen with ALL leg locking ab movements. It's all about positioning & what you're focusing on.

LOL I look forward to trying those & getting WTF looks at the gym

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CK if you are planing on doing those or similar on the decline bench, try VERY hard NOT to pull with your legs. I got to the point I could do a 35 lb plate on my chest without pulling with my legs, just holding me in place... not anymore

have to work my way back up to that... 25's seems fine to me though, heck 10 will do