This is just saying that it needs a driver that supports than GL extension. If you had an Nvidia card then installing the latest proprietary ones (The ones that come in the Xorg Edgers PPA) will solve this issue as seen in the following image:
But since you have an Ati then you are doomed... just kidding ^^. Simply do the following steps in order to have full support (This is my quick way of solving video support issues like this):
Open Dash by pressing the SUPER key (Which is called the Windows key in Windows, in my case it still has the Windows logo on it and I think I got the flu by pressing on it yesterday). Now type terminal. It should look something like this:
Now press ENTER and a terminal window should appear similar to the following:
Now type the following line to install the Xorg Edgers PPA:
sudo add-apt-repository ppa:xorg-edgers/ppa -y
Update and Upgrade system so the system knows you have included Xorg-Edgers:
sudo apt-get update && sudo apt-get upgrade
Install the latest Ati Radeon Drivers which you can do in any of the following ways. I will include them in the order I would do them first (Only do one of the following options):
- Installing the
fglrx-installer package (Which is the one that shows in Xorg-Edgers:
sudo apt-get install fglrx-installer
After this, reboot the computer and you should be finished installing with the Ati Driver. I put this one here first since it is the one that is more compatible with Ubuntu, is updated, less bugs and easy to install. Go to step 4 if you did this.
If you had an Nvidia card, it would also be easier to do just by reading What is the correct way to install Nvidia Video Drivers
- Type Software Sources in Dash. Open the Software Sources Window and go to the last TAB that says Additional Drivers. Look for the proprietary drivers for your Ati there. For Nvidia it looks like the following image but it will be the same for Ati (Just imagine all Nvidia drivers mentioned there to be Ati ^^):
After making sure you have the latest driver that supports your video card and have only installed one of the ones mentioned above, reboot the system and test again. The latest driver makes sure your video card supports the S3TC texture compression. To test this you can do one of the following options:
sudo amdcccle in the terminal. If the Catalyst Control Center appears you are good to go.
Type Catalyst in Dash and see if it appears there.
fglrxinfo and see if it shows information about your video card. If you get "Command not found" or something similar, the drivers are not installed yet.
Lastly if you get a message similar to Required OpenGL extension GL_EXT_texture_compression_s3tc it just means that, either your video card does not support this compression or you are missing installing the correct libraries. If it is the libraries do the following:
sudo apt-get install libtxc-dxtn-s2tc0
I want to also add that there are a couple or articles in PHORONIX about the S3TC issues regarding patents and open source work. It is a good reading: http://www.phoronix.com/scan.php?page=search&q=S3TC
VIRTUALBOX - All of the above is for cases where you were running Steam in Ubuntu on the host, not on the Guest. Since you have just limited Ubuntu to what Virtualbox can offer, I will point you to this link Shared folder between Host and Guest in Virtualbox which should cover the installation of the Guest Addition for Ubuntu. After you have done both, installing the driver and installing the Guest Addition, if the problem is still there, this basically means that Virtualbox is not letting the driver (Inside Virtualbox) read directly the mentioned GLX extension. So the problem would go from an Ubuntu problem to a Virtualbox one where you should go to the Virtualbox site and explain to them the problem.
Let me know if you solve the problem with this little tips. If not I can go deeper with more information. Just trying to make it as simple as possible.