It's the bit in the vid where he says:
"I'm honestly very excited, my family is excited, there's a real buzz about this, it feels right for me"
That one sentence felt very authentic to me. Prior to that talking about his fitness he eluded to keeping himself ready for when the right opportunity came up like this. That says to me he knew he was probably leaving Chelsea, looked at his potential opportunities with his family, we were one of them, we then approached him therefore a relatively easy deal to do.
Probably in a good head space too. It's always nice when a player doesn't feel like they've been dragged kicking & screaming to join us.