Instructions
Turn on your PS3.
Go to the ̶0;Settings̶1; tab in the Cross Media Bar and select ̶0;System Update.̶1;
Download and install the latest system update onto your PS3. As of February 2010, the latest version is 3.15. All system updates past version 2.5 include Flash support.
Open the PS3 Web browser and navigate to your desired Flash video, such as YouTube or any other Flash-based website. You will be prompted to run the Flash plug-in. Select ̶0;Yes̶1; and the video will play.