On mathews website they have a video of a lady shooting a monster xlr8 with her 20yd pin and still hitting the vitals of a 40yd deer target. Would the same happen with the regular monster set at 70#?

That wont happen at all. She is just compensating for the drop by holding her pin high on the target so the arrow luckily falls in to the vitals.

It is PHYSICALLY IMPOSSIBLE for her 20 and 40 pin to impact in the same spot no matter how fast the bow is.

That's not entirely true. Plus it's not accurate as to what was said by the OP.

And the OP was slightly misleading in his post. You should watch the video (good looking girl!!! healthy, too )

She shoots at an elk 3D target with a Monster and a HHA-type slider, single pin. "Mistakenly set at 20 yards and the elk is at 40". An elk's vitals are what, maybe 6" top to bottom? More if you add in the lungs? There's no mention of arrow weight, etc. but the arrow hits 3" or so below where she aimed. That's pretty reasonable for a speed bow.

The physics part is true unless it is being propelled, but I gotcha on the rest

I have an Omen so Ive done their little 20-40yd test just for the hell of it, and let me say first hand... its not pretty...

I used my 45pin at 52yards and dropped over a foot at 340ft/s...

3" drop between 20 and 40 is impossible even @ 400fps I believe. Dont have time tonite to calc this stuff out tho so

a foot of drop from 45 ot 52 yards. Might be stretching the truth a little. 8" maybe, but not a foot!
Obviously, the further the shot, the faster and more drop of the arrow. No matter the speed or the weight.