Just as long as your hand agrees to be filmed, you shouldn’t have any issues. However, if your hand ever decides to get greedy, it may sue you for royalties on every dollar earned on the project.
Y’know… thinking about it, if any part of the body can sign a release form, then it’s the hand.
Oh god… I love you guys. They should make a meeting anywhere in europe, I would definetly come
EDIT: UK would be perfect.
But from the other hand…
Head is most valuable body part and that is why it is hardly copyright protected.
Other parts like hands, legs, wings, bones, etc are also important of course but at least we don’t need release forms.
Best Regards, Andrey