Brief summary so you don't have to watch this garbage unless you want to: he goes through the review he made and stands by it. He clearly hasn't understood the criticism he got.
He goes through that pretty fast, and then gets to what clearly is the reason for this video in first place: to get back, or I'd say really have a revenge and start a smear campaign against Halsey. He, again, makes a point to mention the Pitchfork tweet of Halsey's, and insinuate (plausible deniability) that it wasn't an accident but intentional.
But then it gets to the main thing: he starts going on about how Halsey has in the past kissed her fans on gigs, and he uses a lot of time on this and puts a lot of effort into painting Halsey as suspect, disgusting and immoral, showing pics and even a video of a fan telling a story about it, and putting emphasis on questioning the ages of the fans. In the end of the video he smugly says (paraphrasing from memory) something about people criticizing him are idiots because Halsey is so much worse.
I start my saying that I'm not the biggest fan of musicians kissing their fans, but at the same time I don't think it automatically makes an artist doing so suspect. I think there's nuance and the way it's done matters a lot. If the artist otherwise maintains boundaries that are healthy from the fans point of view, such as not inviting them backstage and hooking up with them, then I don't necessarily see that big of a problem with it, even as I'm not sure if I think it should be done at all.
Anyway, I think this only makes Fantano seem even more misogynistic. He got a lot of backlash for the review, and from a lot of people, and (to me) it looks like he got so butthurt by it and his ego so bruised, that now he's taking that on Halsey and tries to deflect from that by trying to paint Halsey as some suspect and disgusting person who should be target of people's hate instead of him. This is classic DARVO behaviour, which means tactics abusers use: deny, attack, reverse victim and offender. He's doing all of those. Now I'm not saying that Fantano is an abuser, but he uses the same tactics that abusers use. He clearly has no problems with the possibility of launching a massive hate campaign towards Halsey, and all this because she dared to call out his misogynistic review. Oh well. They can't help but tell on themselves. This is such a petty move from him, yet it can get quite serious. I'm afraid this will start a smear campaign towards Halsey, as women get cancelled so easily. I suspect that Fantano knows this very well. And the fact that Halsey is bi makes it even worse for her, as bi women are seen as very hyper-sexual. I can already see how bad this can get.
ETA: Apparently Halsey has apologized for kissing her fans in the past. I'd also like to point out that e.g. Matty Healy from the 1975 has also regularly kissed their fans very recently (not sure if he still does it, but at least a couple of years ago when he was dating Taylor he did), and no one seems to be up in arms about that. Can't help but think that people see this as acceptable when a man does it, but when a woman does, she's seen as an evil predator. Again, I'm not defending that behavior, just pointing out this sexist double standard.
ETA 4: At the time when Halsey did this, she was 18-19. The one fan who's known to be a minor at that time was 17. To me that's not very scandalous, and it's very dishonest from Fantano to leave this out and instead imply that Halsey was an actual grown adult at the time. Idk if he's truly this revengeful and ill-intended, or just fucking stupid and don't understand there being any difference.
ETA 2: I'm not a Halsey fan even if it comes across that way - I genuinely believe what I said and it does not come from the place of being a fan (nothing against her music, it just hasn't hit me I guess). I'm just a gender studies nerd who cares about misogyny and other forms of bigotry.
ETA 3: As someone kindly pointed out, in addition to misogyny, ableism is just as crucial here, as Fantano entirely disregards Halsey's illness and it's largely disregarded in the conversation around this too. Thus, wanted to bring it up here!