I've book-marked the video because I'm fearless (or foolish) when it comes to experimenting with my hair. I might give it a go sometime.
I used to cut my daughters hair in a similar way when she was little. She was born with hair and by the time she was two it needed a trim but she was terrifyingly fast swinging her head around to see the scissors when I tried. Scare that I'd take her eye out I sat with her in the bath with her facing away from me, I combed all her damp hair back into a pony tail tuft (not too high) at the nape of her neck held it and loped of the ends in a single snip*. When it dried it was a perfect Christopher Robin style bob. I had other mums asking if I'd cut their daughter's hair but I didn't think the sitting in the bath method appropriate; it'd never be commercially viable! Her hair grew very quickly but that first cut made sure the ends were blunt which made it easier to brush and made it look thicker.
I also had a responsible adult on hand so that I could pass the scissors to her out of DD's reach straight after the snip!