I am surprised that there is no flash capability in chromium to start out with in Mythbuntu. after some digging around I figured out how to install it. To start Follow the instructions in the Ubuntu wiki. Once you have done that, you need to enable it in Chromium itself as some of it is disabled.

• Open Chromium and type “chrome://gpu” in the url box.
• If it does not look like this then its not fully enabled and you will see some entries listed as software only or partial software/hardware accelerated
• To force Hardware acceleration open up a new tab and type in “chrome://flags”
• find the entry that says “Override software rendering list” and enable it. Then close and reopen the browser
• Now go back to the “chrome://gpu page and it should show everything set to Hardware accelerated.

You should be set to go. ESPN, Youtube should all play videos using hardware acceleration now (assuming you installed your graphics driver correctly).