Do have to have special rights to make a music video of a cover song, or can you simply pay the same mechanical royalty rate you would simply doing a cover?

You need special sync rights, which needs permission and special fees from the publisher. Expensive.

In short : don't do it, unless you're going to do it like the rest of YouTube generation and just do it for free and upload it to YouTube for the exposure, with the full expectation it'll be removed at the request of the copyright owner for being illegal some day.

This special guest forum has now come to an end and is closed for new posts.

It will soon be moved to the Gearslutz.com Q and A archive lower down on the main forum list.

But our special guests will still be able to post on and catch up with questions even though it is in the archive.