I bought this TV mount (from www.dynamicmounting.com). As you can see from the pictures, it easily goes down and back up over the fireplace. My wife can use it easily as well. I'm not a fan of watching the TV above the fireplace--especially when laying down on the couch. This is the only product of its kind that I know and the perfect solution!
Also, admittedly, I'm taking advantage of the company's offer for a rebate if you write about your experience with the mount. I can tell you that I would not be writing a post about it unless I really did like it. I'd be returning it instead! I'm definitely not doing that and am happy to share this with others. Personally, I wish I had stumbled on a post about this TV mount quicker than I did!