Right-click -> Edit site preferences -> Content -> Enable plug-ins only on demand doesn’t help. I still have to reactivate on every new page within the same domain.
I need it especially for playing YouTube Playlists.
Many other people are facing such problems and to solve it follow the steps mentioned by the user in the forum link below -
" The "On Demand Plugin" often doesn't work, some Flash elements still get through. Same with the JS FlashBlocker by Lex.
wonder if this is normal (is it the same with Flash blockers of other
browsers?) or if it's possible to make a 100% working Flash blocker.
The only way to make it work in Opera is to disable it completely (like in opera:plugins).
Here's what I'm using right now:
I leave the Flash plugin enabled (in opera:plugins). (But I disable
other plugins if I have any on a PC (like Java or Quicktime), because
they are security risks and I can do without them when browsing.)
2. In advanced preferences->content I disable plugins
On a site where I want to use Flash (like Youtube) I go to site
preferences->content->enable plugins. (This enables only the
plugins which are already enabled in opera:plugins, it doesn't override
4. On some sites there might be a pop up that says I don't have Flash, but that notification can be set to not appear again.
method seems to work for now, ......"
Also,another user of the same forum described some important points to be considered while enabling/disabling plugins in Opera -
" .......1. The On Demand Plugin isn't site specific.
2. The Flashblock userJS doesn't work on HTTPS (only if I confirm at every restart) + doesn't work in the Feeds
3. The Enable/Disable plugin doesn't make placeholder.
4. The disable plugin with opera:plugins or plugin-ignore.ini isn't site specific."