Open the Opera browser by clicking on the "Opera" shortcut, or by selecting "Opera" from the Start menu. Because Opera may be installed and run on any operating system, use the procedure for opening the program for your operating system and desktop.
Navigate to a site that uses the Adobe Flash Player plug-in. YouTube.com uses the plug-in to display videos. Locate a page with a video. The video placeholder will have an arrow or some other clickable graphic in place of the actual video.
Click the graphic in the video placeholder. The Adobe Flash Player website will open in a browser windows. Adobe will determine your operating system and browser, and provide the download link specifically for your system.
Click the "Download" button once you have verified that Adobe has correctly identified your operating system and browser.
Click the "Save" button to save the installation file to the hard drive.
Click on the installation file, once the file has finished downloading. In Windows operating systems, the installation file will be an executable (EXE) file. In Ubuntu, the file will likely have the extension of ".deb" and may be installed via the Ubuntu Software Center when clicked.
Check or uncheck any third party software options and click "Install."
Click "I Agree" to the Terms of Service.
Click "Finish" when the Adobe Flash Player plug-in has finished installing.
Close any open Opera windows.
Reopen Opera and navigate to a site that requires the Adobe Flash Player plug-in. The Adobe Flash Player now plays the video (or other media) on the page in Opera.