Okay, so he starts showing you content, and you work out that if he's showing you a lot from Person A, that's his current crush, and that makes you feel less than?
To a certain extent, that's a self-esteem issue - and that's reinforced by you saying he was the first man to ever compliment you. It sounds like all of your self worth is built on him, and you struggle when he compliments someone else, because you're so reliant on him, and it feels that him complimenting someone else takes something away from you? I'm really sorry that you feel so low. Have you talked to anyone about this? Do you have any plans for building confidence away from him? It's a precarious place to be, and you don't deserve to be miserable for ages.
Where did the comments on a sexy voice, and her being beautiful, come from, though? I can understand him saying she's really clever. It's difficult because it's not out-of-this-world unbelievable for me to say to DH, "Oh I love this guys' voice", or "He's fascinating to talk to because he knows so much", especially professionally, although I can't imagine commentating on someone's online videos. But equally; I know that DH would be totally unbothered. If I felt he was sensitive to it, I'd make really sure that I didn't, so I didn't worsen that feeling.
I can also see that perhaps he feels he should be able to say those things, and it not cripple your self-esteem, but surely he'd then talk to you about working on that rather than just force ahead with comments you don't want to hear that are hurting you. Has he done that?