Well... I'm sorry I going to be very harsh here (and all my comments are not related to the OP at all)....
First, I agree she's WAY too big for that pony. And frankly I don't get how she doesn't understand it herself. IMO it's something pretty close to abuse.
And second, some stuff she's doing are extremely stupid.
Especially considering bunch of beginners and kids watching that and probably thinking "cool! Why not to try that with my own horse!".
P.S. I do remember discussions here about Nevzorov methods she's using (too lazy to do some search). From this clip looks like he doesn't teach such things as "common sense".