Opera plug-ins
From ArchWiki
Opera is able to use Mozilla plugins, such as flashplayer. Therefor, it is enough to install the desired plugin and add the corresponding directory path in Opera's configuration tool (Tools/Preferences/Content/Advanced/Plugins).
Opera 10
Current Opera already has the correct directory listed, so you don't need to change anything. Plugins like flash work out-of-box if they are installed. Some others, like mplayer-plugin, however still refuse to work.
Troubleshooting
- Restart Opera
- Make sure the directory listed actually contains the plugin(s)
- Reinstalling the flashplugin might also help
Opera 8.51
Note: The following are steps which are not needed anymore.
- Install mozilla plug-ins (e.g. flash plug-in)
pacman -S flashplugin
- Open Tools => Preferences in Opera
- Click on the Advanced tab and select Content
- Open Plug-in options...
- Open Change path...
- Open Add
- Select /opt/mozilla-plugins/ and press OK
- Open Add
- Select /opt/mozilla/lib/plugins/ and press OK
- Enjoy! ;-)