As an amateur artist, I'm always so impressed when cartoonists freehand ink a finished piece, moving from area to area with zero difficulty. For me, I would first be starting with pencil, sketching multiple lines to work out the correct proportions, then adding detail, and finally using ink to tie everything together. What's more, these people are using thick magic markers, which can be hard to control(!)
Oh BTW, the announcer seemed to pronounce two of their last names oddly. For example:
Bretecher = "Mordechet" ?
Druillet = "Doyet" ?
But I'm still learning French, so maybe I'm not hearing correctly.