One of the most popular extensions for Firefox is Flashblock, which prevents flash and shockwave files from being automatically loaded. There have been quite a few ways to achieve the same in Opera, however all of them required some effort on the user’s behalf. The good news is that with Opera 11, this feature is now baked right into the browser.
To block flash and other plugin driven content (other embedded video files, Silverlight files etc.), simply open up Opera’s “Preferences” dialogue box (Alt+P), and browse to the “Content” tab. From here, check the “Enable plug-ins only on demand” box.
Once this option is enabled, Opera will stop loading plug-in driven content automatically. However, you can still load/play the flash videos you want by clicking on the play button (see the screenshot).