Hello from Bulgaria, I've a serious problem, that can't be solved at all.
There is a lot of flickering, while i'm playing video files or flash (or whatever it is: flash, windows video media net streaming, quicktime... any kind of video playback) clips in firefox (http://youtube.com/ for example).
It makes no difference, if i'm using the opensource ATI driver - radeonhd or the propriety driver - fglrx (i've tested the whole version tree from 8.33 to 8.493).

This is my original 'xorg.conf' file:
.................................................. ..............

Section "Files"
InputDevices "/dev/gpmdata"
InputDevices "/dev/input/mice"
FontPath "/usr/share/fonts/misc:unscaled"
FontPath "/usr/share/fonts/75dpi:unscaled"
FontPath "/usr/share/fonts/100dpi:unscaled"
FontPath "/usr/share/fonts/Type1"
FontPath "/usr/share/fonts/URW"
FontPath "/usr/share/fonts/Speedo"
FontPath "/usr/share/fonts/cyrillic"
FontPath "/usr/share/fonts/truetype"
FontPath "/opt/kde3/share/fonts"
FontPath "/usr/local/share/fonts"
EndSection

Section "ServerFlags"
Option "AllowMouseOpenFail" "on"
Option "ZapWarning" "on"
EndSection

Section "Module"
Load "dbe"
Load "type1"
Load "freetype"
Load "extmod"
Load "glx"
EndSection

Section "InputDevice"
Driver "kbd"
Identifier "Keyboard[0]"
Option "Protocol" "Standard"
Option "XkbLayout" "us"
Option "XkbModel" "microsoftpro"
Option "XkbRules" "xfree86"
EndSection


Section "InputDevice"
Driver "mouse"
Identifier "Mouse[1]"
Option "Buttons" "12"
Option "Device" "/dev/input/mice"
Option "Name" "Logitech USB Optical Mouse"
Option "Protocol" "explorerps/2"
Option "Vendor" "Sysp"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
Driver "synaptics"
Identifier "Mouse[3]"
Option "Buttons" "5"
Option "Device" "/dev/input/mice"
Option "Emulate3Buttons" "on"
Option "HorizScrollDelta" "0"
Option "InputFashion" "Mouse"
Option "Name" "Synaptics;Touchpad"
Option "Protocol" "explorerps/2"
Option "SHMConfig" "on"
Option "Vendor" "Sysp"
Option "ZAxisMapping" "4 5"
EndSection


Section "Monitor"
DisplaySize 367 230
HorizSync 30-82
Identifier "Monitor[0]"
ModelName "LGPHILIPSLCD LCD MONITOR"
Option "DPMS"
Option "PreferredMode" "1680x1050"
VendorName "LPL"
VertRefresh 43-60
UseModes "Modes[0]"
EndSection


Section "Modes"
Identifier "Modes[0]"
Modeline "1680x1050" 147.14 1680 1784 1968 2256 1050 1051 1054 1087
Modeline "1680x1050" 117.00 1680 1728 1760 1840 1050 1053 1059 1080 +HSync -Vsync
EndSection


Section "Screen"
DefaultDepth 24
SubSection "Display"
Depth 15
Modes "1680x1050"
EndSubSection
SubSection "Display"
Depth 16
Modes "1680x1050"
EndSubSection
SubSection "Display"
Depth 24
Modes "1680x1050"
EndSubSection
SubSection "Display"
Depth 8
Modes "1680x1050"
EndSubSection
Device "Device[0]"
Identifier "Screen[0]"
Monitor "Monitor[0]"
EndSection


Section "Device"
BoardName "Mobility Radeon X1600"
BusID "1:0:0"
Driver "radeonhd"
Identifier "Device[0]"
Option "monitor-PANEL" "Monitor[0]"
VendorName "ATI"
EndSection



Section "ServerLayout"
Identifier "Layout[all]"
InputDevice "Keyboard[0]" "CoreKeyboard"
InputDevice "Mouse[1]" "CorePointer"
InputDevice "Mouse[3]" "SendCoreEvents"
Option "Clone" "off"
Option "Xinerama" "off"
Screen "Screen[0]"
EndSection


Section "DRI"
Group "video"
Mode 0660
EndSection

Section "Extensions"
EndSection
.................................................. ..............



I've also tried some tweaking in the 'xorg.file' like:
Option "TexturedVideo" "off"
Option "VideoOverlay" "on/off"
Option "OpenGLOverlay" "off"
Option "XvmcUsesTextures" "True"
...
No difference !

My current distro is openSuSE 11.0, but this is a common issue for me, which occurs also under Ubuntu 8.04 LTS, Mandriva 2008.1, Fedora 8/9, Slackware...etc...

Any suggestions !?!
Or it's an ATI driver drawback.

Maybe a problem with the driver(s). Only CRT monitors may flicker at times.

Test it with vesa for example... then if the same thing happens, there is a problem with the monitor/card.

I've already tried 'vesa'. I forgot to mention and 'fbdev' also. The problem persists again, but there's less flickering. I should specify that there's flickering when the objects move on the video, if they are motionless - no flickering.
Under WinXP - i've never noticed ANY flickering. The card is ok, the monitor is LCD Widescreen, 17 ", 1680x1050. The computer is a HP nx9420 rh450ea laptop.

Is there probability, the reason to be the Xorg server, not the video driver ?

No solution yet...

Misconfigured system? At this point you might as well try something else... There are live-cds that allow you to add video drivers on the fly like BackTrack.

I don't think so... this problem persists in several other distributions like i said.

What's this for ? I've tried 'radeonhd', 'fglrx', 'vesa', 'fbdev'. Why i need drivers on the fly ?

I don't know. Try and see if you can make sense of it yourself.

Super. )

What are you using to play videos.

I had problem using xv and xvmc as a video driver. Xine and maybe mplayer seem to default to these.

For xine try using xshm or opengl. opengl just now worked for me even though fglrx is temporarily missing so I think mesa is working.

For mplayer try using gl or x11 (gL and xoneone)

If using command line put vo=gl in your /.mplayer/config file
If that doesn't work try vo=x11

This fixed my video problems in these programs.