My mom is going to get a flat panel TV soon. I'm trying to find a wall mount that will swing the TV from the Family Room over to the Dining Room. I've attached a lame sketch and I think I found a mount on Amazon that might work.

The two rooms are separated by a short 3 foot wall. The end of the wall goes all the way to the ceiling (dark line). The wall is about 4-5" thick (so I don't think I can mount it on the end. The distance between the edge of the wall and the exterior wall is about 3 feet. She is looking at a TV about 40-50". I can't quite tell if the two arms on the VideoSecu are long enough. The first arm will need to lay flat against the short wall and it will need to clear the end of the mount. The second arm only needs to swing the last 90 degrees.

If I'm not making any sense let me know.

http://www.amazon.com/Articulating-Plasma-Panel-Mount-32-55/dp/B001020DZO/ref=sr_1_47?ie=UTF8&s=electronics&qid=1238458957&sr=8-47

http://i196.photobucket.com/albums/aa155/Nightmare_pics_999/Moms.jpg

My mom is going to get a flat panel TV soon. I'm trying to find a wall mount that will swing the TV from the Family Room over to the Dining Room.
You can make this work with a single arm articulating mount, but you'll want a very high quality unit such as the Peerless PLA-60 since you're planning to hang a large (40-50") screen with just one arm support.

With dual arm mounts you can get by with reasonably priced but good quality Monoprice mounts. However, single arm mounts are another story, they're just inherently less stable and need absolute rigidity to stay level throughout their full swing of motion. Check the Amazon user reviews on that VideoSecu unit, they're pretty clear it's low cost and you get what you pay for, particularly with regards to unit sag under load. Then check the following thread for pictures of what happens to a cheap single arm mount under full load:
Articulating Mount (extended) (http://www.avsforum.com/avs-vb/showthread.php?t=1109632&highlight=)

I have the Sanus VMAA single arm mount, which is very rigid, but the Peerless has a longer reach and variable pivot mounts, which may work better for your "round-the-corner" application. Note that Costco carries both these mounts online, which is handy because they'll refund full price with shipping if it doesn't quite fit. Expect to pay $250-$350 for a good single arm mount.

Would the mount for your TV reach around the corner?
It looks like the first section of the arm will need to swing flat against the wall and it needs to be long enough to let the second part of the arm lay flat again the 4" end of the wall.
It is hard to tell if the PLA50-UNLP arms are long enough.

I have the original Sanus VMAA, equivalent to the current VMAA-26. I just tried measuring it, and it looks like the first arm section would extend about 2-3 inches beyond the edge of the base plate when laying flat. To make that work, the VMAA arm carrier base would need to slid all the way to the left on the base plate.

That Peerless PLA mount wasn't available back when I installed the Sanus. However, it's got a longer extension reach, so I assume the arms are longer and would provide even more clearance.