Lebrera came in heat eight days after the foaling, and she showed that she was ready to be together with Fabuloso again. He is very happy about this and is showing off to her as much as he can.
Although she is showing very clearly that she wants him to breed with her, he isn’t quite sure that he is allowed; he has been with mares before and knows to take it slow. Experience tells him to be careful with those hind legs, and she gets a bit annoyed with him for not understanding that she is ready.
Lebrera is clearly torn between her concern for the foal while at the same time wanting to be with him. The clip is just showing a few scenes of this interaction; in real life this lasted for two hours before the actual breeding happened.
To often a stallion and a mare are not allowed to have this interaction and flirting process with each other, and many stallions are taught just to jump up and breed without any chance to get to know the mare at all. The mare is tied up so she is not given a choice in the matter. The reason is of course the safety of both of them, but the price of this form for breeding is that is depriving both horses of a very important part of their natural behavior.
This, combined with the fact that most stallions don’t get to live with his mares, is probably the reason that so many people sees stallions as something dangerous and think he will jump on any mare given the slightest opportunity.