Okay, so Demul didn't work with 3D Ripper DX and it was very laggy. But! It seems that ripping models works only on Windows XP. And it did work, but only partially. Models were flat. I have to figure it out!
Weird, it has the same problem with the original Rayman 2 version : the models are ripped as flat. Maybe some settings tweaks in Demul could help but I don't think there's any way to fix that though.
I figured it out! NullDC and stereoscopic 3D plugin helped me. And it looks not bad. Unfortunately, textures haven't saved and there are some missing faces. But overall it's good.
Huh, it looks so...different without any of the textures. You could plonk some sand and rock textures and it'd make a nice desert, as opposed to the set of islands it was.