Gee, I just watched that video a few weeks ago. I had my 1913 model T over at a friends house in a warm shop. I came in with the garbage bags and some new 30 x 3 1/2 tires to mount. I told Chris how EASY this was going to be " don't help me, I can do this my self!"
I thought poor Chris was going to laugh so hard his beer was going to come squirting out his nose! I did get the tire on (with help). The second tire went MUCH faster without the bag(no garbage bag to try to dig out from between the clincher rim and tire)!!!!!
All have to say is those zx@#$ ing bags are for GARBAGE! not mounting tires!!!!!!!.
*Results in you area may vary, not good with other offers, some side effects include swearing , heavy drinking and laughter.