Thanks for supporting Samsung products.
The Auto Motion Plus is picture processing. It takes the signal and processes it with the idea that it will improve the picture. The reason it is defeatable (why the "off" mode is available) is because we recognize that everyone sees the picture differently, and might not want the additional picture processing. Some people like the settings on High on every input, and some just like High on Blu-Ray, or Low on Blu-Ray and High on Satellite television.
Either way, every input has a specific setting, so if you like High on one, Low on another and Off on a third, you make those settings and they will be input specific.
Thanks for your kind words!
Just got the TV this past Sunday and Love it. I kinda like watching everything with the AMP on high. This is good because there does not seem to be a difference in off, low, med or high. Shouldn't it be close to a normal HDTV when it is set to off when watching normal HD directtv?