It's a great video and what is really amazing is that the other Susannah can hold a plank, talk and do multiple plank variation exercises all at the same time. Just holding a plank for one minute is no easy task and I conclude that she must have abs of steel. Steel City is a good name, I think.
The dog variation is remarkably similar to the Yoga cat stretch I used to do and probably should start doing again. It's also not unlike the dive-bomber push-up and Hindu push-up. Slight changes of emphasis probably.
I have now subscribed to the videos under my youtube moniker.