HoMM VII Haven Units – Haven faction units from the seventh installment of Heroes of Might and Magic.

Is it available for download, or is it only available as a video?!

Yes, something like that. FrozenSol didn't really show off these things on the forum; we discussed them in private messages.
At the time we were discussing it (a couple of months ago), everything was 90% complete; all that was left was to render the texture in Substance Painter. What happened next, whether FrozenSol abandoned the manticore or not, I honestly don't know.

Added 12 minutes ago

But you, Zakhar, shouldn't be so harsh; the manticore, and everything else, is really cool.

Indeed, they are interesting models, but Footman has nothing to do with them, so his contribution to their creation is zero.
Do you want to convert models from Heroes 7 in the same way? Just read the manual here on the forum. Do you want models from Heroes 6? Also, check out a video on YouTube about attaching a model to bones.

It's all very simple. It can be tedious, long, and annoying, but nevertheless, it's still very simple. There's nothing outstanding about this work. And I don't quite understand this whole thing where Footman is trying to get compliments and other accolades. If this is something else, and I haven't understood everything correctly, please correct me.

I just sincerely wonder why he "teases" people with screenshots and other "super-secret knowledge" while taking the position of "it's all mine." It's strange. "I have a package, but I won't give it to you." It's like we're in kindergarten, and someone bought a new toy.)) In short, it's both funny and sad. Although, of course, it's mostly funny.

Added 2 minutes ago

Maybe Footman is also Goose, which is why there are so many tricks and intrigue?

Sometimes I wonder, maybe everyone on this forum is Goose? Maybe I'm also Goose? You can't be sure of anything, you know