Get a deeper stance. Put the anchor hand (your right in this video) now under your butt cheek like you're repelling. The left hand is there to guide the line *only*. Deeper stance, and you can not get moved so easily. Thats why the dog got a grip it wasn't supposed to get.
Stand like this. Theres a reason its done in Martial Arts... stability
Hunter, USA trial helper, Charleston Working Dog Club Training Helper/Training Director
Beschützer des Jägers v. Sportwaffen, HOT, IPO1, AD, CGC
Katya v. Hügelblick, HOT, IPO2, CGC
SG Aska v. Ketscher Wald, 2 x SchH3, Kkl 1