The current Flash 9 Browser Plugin for Linux requires the browser to support GTK. As Opera for Linux is QT-based, it does not offer a GTK-API to plugins. Opera 9.5 Release Candidates now implement GTK support. However, Opera 9.5 is far from stable, and not suitable for production use (= my experience).
If you have accidentally installed the current Flash plugin (r.115), or your package manager upgraded it automatically for you, this means no Flash support in Opera 9.20.
However, there is a quick workaround:
- Uninstall the current Flash plugin.
- Download a ZIP archive with all Flash 9 Plugin versions (73 MB) from Adobe.
- Extract install_flash_player_9r48_linux.tar.gz from the 9r48 folder in the archive.
- Extract libflashplayer.so from the tar.gz and put it e.g. in /usr/local/lib
- In Opera's plugin preferences add this path to the plugin paths and re-scan for plugins. Opera should detect the Flash plugin and use it from now on.
- Watch funny videos on Youtube