I didn't finish the video, so my apologies if this is actually addressed later, but the central thrust that Astarion is not threatening, particularly in terms of sexual violence, and that this is his appeal just seems to be completely false. I couldn't get further because it seemed so detached from reality.
If he dislikes you, he can get aggressive. More so than most of the other companions, even. If you fail the rolls in the scene where he drinks your blood it is quite intentionally using the cinematic language of sexual assault. You beg him to stop, he doesn't. You try to push him off, he pins you down. He kills you. If you have your party resurrect you afterwards, he shows no remorse. He tries to excuse it by saying he lost control and acts like it wasn't a big deal. He is literally introduced putting a knife to your throat.
He is controlling and manipulative. If he likes you, if you do what he wants, you just get the harmless fop. If he doesn't then that mask quickly drops.
So I got the exact opposite read on him. That he was dangerous, potentially sexually violent. He reminds me of a type of guy who uses trauma, even genuine trauma, as a shield for their own abuse. The "I'm just a sad boy" routine.
I've even talked for awhile with a friend who was really into Astarion about it when we played BG3 together. For her, the danger was part of what she liked. That's kind of the norm with vampire romance fiction and I don't think Astarion breaks the mold. The idea that a dangerous monster will change for you.
He's also pretty devoid of empathy for anyone he personally doesn't like. Encourages murder and torture constantly, approves of you backstabbing people and fucking them over, and is generally kind of a dickbag.
All the characters are well-written though, because they're all multifaceted like this, and deeply flawed. Both of these assessments of Astarion are true, I think. He has good reasons for being the way he is, and if he's nudged in the wrong direction he easily becomes just as foul a monster as his master was. Nudged the other way, he learns to mellow out a bit and accept that he doesn't have to hurt people before they hurt him.
I found a YouTube link in your post. Here are links to the same video on alternative frontends that protect your privacy:
