If you pair program with someone else on your team, you both learn what the other is thinking. You both become more familiar with what the code is doing, and why it's doing it.
If you "pair program" with an AI, anything it learned, it forgets as soon as the prompt is closed.
So don't think that's what he's talking about here. He's talking about XP, with humans, just like in the 1990s. There may be some AI in there too, but that's not where the XP part comes from.