The problem described by Cokol (at the top) may be explained, and fixed, by understanding the video acceleration modes. There are two modes, UXA and SNA. UXA is the older, more mature mode. SNA is the faster, newer mode, but it's less stable. If you have the onboard Intel 865G integrated graphics like Cokol, you need to be in the UXA mode.
Trouble is, Linux selects the SNA mode by default (as of Aug 2013), which completely screws up adobe flash-based videos (regardless of browser) running on the older Intel graphics hardware like 82865G (and others). It fools you, though, because the rest of the system looks like it's working OK. But it's not.
The "fix" is to get your system booted up in the UXA acceleration mode. In order to do that, you have to write a little configuration file, and save it in the right place. The following steps fixed my Dell 170L graphics, and now instead of green and purple mish-mash, I see beautiful, smooth video.
Open the Terminal, and type "gksu gedit" [enter]. It will ask for your password; type it, then press [enter].
In the text editor that pops up, enter this exactly as shown:
Identifier "Intel Graphics"
Option "AccelMethod" "uxa"
Save the file in /etc/X11 with the name "xorg.conf". Exit both the text editor and the terminal, and restart your computer. You should now see the correct video, in an acceleration mode the 865G understands.
If for some reason this doesn't work for you, just delete the xorg.conf file you just created, and you'll be right back where you started before saving the configuration file.
Ref page: https://wiki.archlinux.org/index.php/Intel_Graphics
...see "Choose acceleration method", and "Corruption/Unresponsiveness in Chromium and Firefox".
Ref also this: http://ubuntuforums.org/showthread.php?t=2195590&page=2