As I can see on the video, the elbow part is messed up, have you checked or tried other animations aside from this dance anim if the model has been skinned properly?
I disagree with this one, if the script works, then that should work, you should know how the bone hierarchy works. 'Coz if the animation is exported from a different game then it's a different story. If you're trying to import a dance animation or any animations you want, I would recommend you to check on how to transfer animations from one rig to another.