I always enjoy his science-based videos. Towards the end of this one he pointed out all the studies were on stationary bikes and didn't include climbing or sprints, and they pretty much focused on efficiency gained from pulling up on the pedal not being pushed down. I remember years ago being told measurements show no one (including pro racers) was really pulling up, but they were taking more weight off the pedal going up.
On my gravel bike I have dual sided pedals - I use the flats when riding with my wife at lower speeds on paved trails. or on commutes where I don't want to carry extra shoes or clip in/out every few blocks. Kinda like on the stationary bike at the gym, not much difference in my speed on those rides whether I clipped in or rode flat side on those rides. But, on the occasional hilly ride on less than perfect surface in sneakers on the flat pedals, I find my feet are all over the place and I am definitely slower climbing and overall speed on the same ride.
A lot of the science around why skinny high pressure tires are not always faster than fatter lower pressure tires came about when the tests started to be done on realistic road surfaces and rides simulations - would be good to see the same kind of tests here.