I didn't see that the video disproved Newton's Laws of Motion.
It was clear that in decelerating lines, the fuel sloshed forwards and in accelerating lines, it sloshed backwards.
Frankly that would be obvious to anyone who understands mechanics.

If you have problems with fuel starvation and you are using tank pressure then I would recommend the following (not necessarily all together)
Wider bore fuel lines
A longer length of fuel line (coiled once if necessary, coiled twice and it's too long)
A bigger fuel filter to act as an accumulator, Saito F1's are nice (but pricey).
A 1/2 oz or 1oz auxiliary tank next to the carb .
A Perry VP20 or VP 30 pump.
A baffled tank.

I fitted one of the Perry pumps to an Irvine system I had because I was getting poor pick-up on opening the throttle. Fabulous! It was like revving a motorbike afterwards.

Hi!
As I said ...Engines runs due to the remaining fuel in the fuel line...when engine has sucked it up it stops...but it takes time! Several seconds ...and most of us don't dive our planes straight down for several seconds. I have never in my 35 years flying R/C experienced an engine stopping during straight down dives!

Could you not just use a small header tank the same as the heli guys use, or use more flexible tubing, like helis use, they stay in all sorts of position for long periods of time.