When she points out that a dog refusing to do something might be doing so because of an injury, I thought that was interesting, but it sounded to me like she was saying because it's possible that the dog is refusing because it hurts, you should never insist; I feel that would be to the detriment of my dog.
Elsie is a naturally reactive dog, who finds the outside world very stimulating. I know that by learning to stay calm even when faced with confusing or frightening stimuli, she has an easier emotional time of it. It would not be fun for her to be on edge all of the time. When she 'refuses' to sit on a walk because there's a hawk on a light pole a half block away screaching (real thing that's actually happened), my gently saying, "Whoops!" and walking in a tight circle with her and asking for a new sit... I don't think that's a bad thing. I think the risk of her learning that 'sit means sit unless there's something weird happening in which case you should probably ignore the human and be really really concerned' outweighs the risk that between the front door and the sidewalk she's hurt herself.
And yeah, ideally I never would have let her go 'over threshold' in the first place and she'd never miss a cue, but I'm not that good of a trainer. ;]
On the other hand, the above mess is probably not what she was talking about; it was just my thoughts while watching the video.
I do let my dogs do quite a lot that they could get seriously hurt doing. We bike with them, and Zobby HAS run under the bike before. Luckily, he wasn't injured but he could have been. I hike with Elsie, and we often hike in places that she has to climb rock faces. In that situation I use social pressure to get her to do something she's mentally uncomfortable with, and I'm glad I did; the first time she was like, 'aw hell naw people die that way yo' and I kept walking, she got all upset about being left, and scrambled up. The next time we hit the same kind of scramble, she was like 'i got this let's go' and did it. At the same time, I don't let her jump down off high rocks; I make her wait, and then help her down. Still, she could break the down and leap. She could slip. But she loves hiking, I love hiking with her... I think it's worth it.
At the same time, I do think it's important to keep the dog's limitations in mind when doing things; it's important to think about the possibility of injury. And I think for me, in that, the video was successful. I did think. :]