play good on your pc? Ive had problems like this where I was sure the file was good only to find out that it must have screwed up during conversion and plays the same way on the pc.
I have a bunch a movie files an a USB stick on the side of my UE40C6005. Playing those is really a hit-and-miss experience. Some work some don't. Those that do not work play audio but the screen remains blank.
I have encoded the movies with the same software using the same H.264/MPEG-4 AVC high profile settings. Why some of them work and some not I think is due to shoddy playback codec on the TV.
I would be more than happy to provide Samsung movie samples should that improve the chances of them ever fixing this issue.