"Stiff side" and "hollow side" - deconfuse me please!

[renta]

My horse is pretty even at the moment. But when she becomes worried about something outside  she pulls her shoulder in and falls into a tighter circle and she used to go off a circle to the outside on the hollow side. You didn´t misunderstand what she said.

[Hammie]

OK, will have to watch this again later - no sound at work. I was looking at the list near the end though, and am still confused. Snowstorm is difficult on the right rein and easy on the left (left-bended horse), but goes out on the right rein and falls in on the left (right-bended horse), and the saddle slips to the right (left-bended horse). Much of the other stuff I'm too much of a schooling numpty to notice!