Yes, these are real cadavers.
This is an educational YouTube, and I really enjoy watching it. The instructors are very respectful of the donated bodies, and they make sure to keep all pieces of the body together so they can be cremated at the end of their agreed upon term.
It’s really interesting to see how all of the parts go together. It’s one thing to see it in a drawing in a book and another entirely to see it in 3D.
So, if you’re interested in Anatomy, you can check out this channel here.