"He thought about getting (or making) a Pop Up TV cabinet to hide the TV, but he did not want to replace or modify the furniture he already had in the room," explains Instructables' user hiddentvguy. "We solved the problem by using a TV lift system to mount the television behind the existing cabinet."
The $1,350 system is made by Nexus 21, and is only 23 inches tall. They installed it on the wall behind the cabinet, so the cabinet acts to hide it when the TV is down. "The total distance between the wall and the back of the cabinet is about 8 inches (3 inches for the TV, 4.5 inches for the lift mechanism and 0.5 inches of clearance)."