As I explained, I have no /etc/X11/xorg.conf file, but I didn't remember that, in the past (perhaps 2 o 3 years ago), I added some options to the grub config in order to make the boot process in text mode (instead of in graphical mode). I remember that I added the options due to a problem when playing videos, and it was fixed by booting in text mode.
I don't remember too much, but it sounds to me that the x-server was started twice: Once for the boot process, and once for the graphical login. I did read in some forum that, by adding some options to the kernel and by booting in text mode, the x-server would be started only once, so the problem would disappear. And the problem disappeared.
Everything looks fine. I suspect the HD videos may just be more than your CPU can handle. At the moment, the driver only handles rendering (color space conversion and scaling) on the GPU. Decode (mc, idct, etc.) is still done on the CPU. You might try the multi-threaded ffmpeg if you have a multi-core CPU.
the CPU keeps at 20-30% of usage in full screen. But, just at minute 2 (2:00), the camera walks vertically on an hotel, and I can see crearly that the walking is not fluid. This happens both with monitor or with tv.
Perhaps the problem is what bridgman said, that fedora 13 has not good support for my card?