Yeah, I don't think I am going to watch the videos because I am 99.9% sure I'll have the same reaction to them.

Although, I know what sensation they're talking about - I've had that sensation before just by someone being kind to me unexpectedly. I always assumed it was some sort of cortisol thing from the experience of being nurtured. Some sort of natural instinct we have to relaxing when someone shows they care so that it encourages us to continue to care about each other.