RE: TV Mounts
I agree with you Ed, a 4 lb tv times 4 is 16 lbs and that's just what that mount is rated at. However, any thing heavier may require something a bit stouter.
Just after Christmas of 2010 my G. daughter had Wal-Mart sourced wall mount snap off on her as she was repositioning a newly mounted 22' flat screen she had just gotten. Fortunately she wasn't injured, but the 1 month old TV became scrap from the fall
When I use the mount I mentioned in an RV, I use a piece of 1/2" plywood, at least 10" x 18", on the back side of the wall I am attaching the mount against to distribute the load, and I also tie them in close to the wall with bungee cords for travel.