I'm glad he posted the video. One thing he didn't mention that is striking to me is how high his hand is on the page, essentially resting above the line he is writing, with his thumb parallel to the line. Whereas as a right-hander, my hand is essentially centered on the line, with my thumb at a 45 degree angle to the line.

Do most left-handers learn to hold their pen/pencil like that? If not I imagine it would be quite a transition to adapt to as all the motions are rotated - the portion of the stroke previously done by moving fingers in and out would instead be done by moving side to side, and vice-versa.

Edit: Or from trying it, I guess you could just write as normal and end up with everything italic/slanted.