My preferred technique is to also start with the cover inside out. Then put your hands inside the cyber into its corners. Then grasp two corners of the duvet through the fabric. A bit of shaking to turn the cover the right way out and you are done.
There was a program with Jacques Martin about "incredible" stuff. I remember a hairdresser who used a flame and J Martin almost agreed to try, another one about the world record in going back and forth through a door.
That one was the world record in how many duvets you can handle in a given time IIRC.
Note that this was 80, 81 or around that. This was the only source for such stuff in France so it was a big show (for children at least)