Been working on this for hours yesterday and giving up now. Time to ask for support!
I've got to get HW decoding working for videos on my netbook and have installed the ATI drivers and the gstreamer-vaapi plugin from:
http://packages.atrpms.net/dist/f15/gstreamer-vaapi/
Running Totem and opening a video gives:
libva: libva version 0.32.0
Xlib: extension "XFree86-DRI" missing on display ":0.0".
libva: va_getDriverName() returns 0
libva: Trying to open /usr/lib64/dri/fglrx_drv_video.so
libva: va_openDriver() returns -1
Segmentation fault (core dumped)
Which is because the fglrx_drv_video.so doesn't exist. It doesn't exist on the system and isn't provided by ATI. Inb fact, it doesn't seem to be provided by anybody!
Anyone got any hope to offer?
// An ex. Slack user in need.

---------- Post added at 09:54 AM ---------- Previous post was at 09:39 AM ----------
Ok found the darn file 5 minutes later. Now getting...
libva: libva version 0.32.0
Xlib: extension "XFree86-DRI" missing on display ":0.0".
libva: va_getDriverName() returns 0
libva: Trying to open /usr/lib64/dri/fglrx_drv_video.so
xvba_video: XVBA_CreateContext(): status 11
libva error: /usr/lib64/dri/fglrx_drv_video.so init failed
libva: va_openDriver() returns -1
Sigh

---------- Post added at 12:19 PM ---------- Previous post was at 09:54 AM ----------
Fixed it. Will power at work.
In this order...
Recompile libva from latest source at website.
Symlink the DIR called /usr/lib/va/drivers or whatever it is vainfo complains about to /usr/lib64/dri/.
Get the xvba packages and copy the flglx_dri_video.so file and the other one inside it into it.
Remove the ATI RPM packages from fedora if you have installed them.
THEN run the ATI 11.8 installer.
Next, download VLC and all plugins. Go to the options and click hardware decode. All 1080p now works!
Gstreamer/Totem will not work at all. Forget it.
Latest Flash 11 RC1 released this month works with VAAPI and works nice. My Acer 522 is just too slow to handle 720p through Flash but its watchable.
What a nightmare the whole thing was.