I have my doubts about them going to true failure as well, especially considering they only rested for 1 minute in between sets. How can you do a set of squats (or leg presses or...) to failure and then after only one minute of rest do it again? Even with decreasing weights, this seems very unlikely to happen. If they really did do it, those guys were machines to say the least.
My opinion.
There is 'failure' and then there is "failure". If you go you real failure you will not want
to do another set. If you haven't vomited after a set of strict standing barbell curls, then
you have not worked hard enough. Most people working to so called failure are nothing
but a collection of facial expressions, fake noises, dropped weights or falling to the floor
feigning great pain and total failure.
Example.
I once knew a man who did very little in the way of exercise but got spectacular results.
You would not know it by looking at him that he was working hard. Very controlled,
strict movements. He was quiet, his face was calm, devoid of any facial expression
except extreme concentration. But you could see his muscle pumping up, grinding out
rep after rep to failure. Then partial movements until the bar would not budge, literally
dropped from his hands. Then on to the next exercise. No talking, just total focus.
He walked the talk.