No, you’re not hallucinating, this is really Loki, Tom Hiddleston, doing a screen test for the role of Thor. It’s part of the Thor: The Dark World DVD extras, proving that yes, it’s still worth it sometimes to have DVD extras.
Now, I’m not sure if Hiddleston ever actually auditioned for the role, as that seems rather…unlikely given the physical dimensions required to play the part, or if this is some sort of gag thing they did for the DVD.
I’m sure someone out there knows the answer, and I’m about to find out. School me.