EDIT: I looked in my parts bin, found the inner tube I originally cut up
It says "Axiom - MADE IN TAIWAN 1.9 / 2.125". Just now I cut a new 1" cross section, used 3 fingers from each hand to stretch as hard as I can pull with all my strength to try to snap it.. it wont snap! It does reach a point where it won't stretch out any further.
It occurs to me that not all tube brands would necessarily be the same rubber compound or stretch out in the same predictable way, so your mileage may vary considerably. Mine luckily worked perfect first try!
I ended up layering 3 cross sections around the heel of the pedal to make the tension a little tighter for my liking.
Both my pedals have been perfect ever since, still going strong with the same inner tube sections from when I made that video 3 + years ago. I never kept the blue rubber bands on long enough to determine longevity, but I'd suspect the bike tube is way better quality rubber.