Watched it with some friends yesterday, don't think I got all of it, so can't really remember if he talked much about Barca, but the host seemed more interested by what he had to say about the French NT (which is pretty normal, considering it's a french show, and it's his first appearance since we won the WC).
He didn't say much, honestly. The general tone of the show is always pretty superficial, so he said some pretty basic stuff about French NT, said he wasn't afraid to lose his starter position after his pretty dumb penalty against Australia because he knew what he was capable of. They also talked about the fact that it took a couple years for him to become a regular starter with France NT (he wasn't even in the group for Euro 2016 at first, and managed to secure a last minute spot thanks to Mathieu giving up), and again he said he's always been confident, and he knew that some players needed more time than others.
He also talked about what he felt when France won, and what he's been feeling since then (the host mentioned that Deschamps said that winning the WC will change all of them for ever, and Umtiti obviously agreed).
Said a couple things about his belgium goal celebration. Basically, it's a silly walk he does sometimes with his friends. He did it in the locker room before the beginning of the game, not knowing that Deschamps was looking at him, so everyone made fun of him, and that's one of the reasons why he did it after scoring.
They showed a spot about kids from the club he used to play for before joining Lyon, where the kids asked him to: score an overhead volley instead of a header next time; stop using his hands; bring the WC to their tiny club someday, and also bring his France and Barca jerseys, "and Messi !". That was a pretty nice moment, made him laugh and he seemed slightly touched.
Oh and there was the whole thing about Vegedream by the end of the show. Basically, Vegedream is a guy who sang a rather generic song about France NT for the world cup. It came out between the semi and the final iirc, and the chorus is about Umtiti's weird walk. The singer was invited to sing the song, he sang like 15 seconds, and then just stopped the song to ask Umtiti to do the walk. Which he did, like nobody was watching (that's the second clip from your post).
All in all, even though he didn't say anything really out of the ordinary (but then again, nothing truly shocking ever happens during that type of show), he came out - as always imho - as a really laid-back and nice guy.