Sold out on Amazon with great reviews, it was priced at $250 plus taxes.  
 
Mount-It! Pull Down TV Mount for Fireplace Mantel Installation, Height Adjustable Fire Place Mantel Mount, Down and Out Full Motion Design, Fits 43-70 Inch TVs, 77 lbs Capacity
 
FIREPLACE TV MOUNT: Mantel TV wall mount designed specifically for fireplace mantel use. 23 inch height adjustment allows TV to be pulled down to a more comfortable viewing height.
GAS SPRING HEIGHT ADJUSTMENT: Counterbalance mechanism assists in lifting and lowering the TV. Allows fluid, tool-less height adjustment. Spring tension adjustable to suit your TV weight.
CERTIFIED SAFETY: Certified TV mount strength tested to 4 times the rated load to ensure it is safe for both your equipment and your family. 77 lbs carrying capacity.
UNIVERSAL FIT - Fits TVs from 43 to 70 inches in size. Compatible with VESA 200x200, 300x300, 400x200, 400x400 and 600x400 bolt hole patterns.
FULL MOTION DESIGN - TV can swivel left and right 30 degrees, tilt 5 and 12 degrees and rotate 3 degrees for ultimate TV angle adjustment for your comfort.