I don't think he disproved the scoop, just that you don't need tons of traction to do it.I often see mtb jumping advice about getting more traction to help keep your feet on the pedals. Coming from freestyle BMX I knew this wasn't true. You can take your feet on and off in the air with good technique. I run plastic pedals with tiny plastic nubs on my DJ which are totally fine for hopping and jumping. Most riders whose feet accidentally come off are getting bucked (poor technique). However, even knowing this I was still excited to see someone put it to the test.
Disclaimer: having decent pedal traction is a good idea for mountain biking in general, especially for beginners. Just don't blame your pedals or shoes for jumping technique.
As someone who has walked around on a plywood sheathed roof on many an occasion, I can tell you that there is definitely traction between sneakers and plywood.