This is not due to Flash, but due to HTML5 / H264 / MP3 video/audio not working correctly (YouTube/Spotify/Facebook don't use Flash for music/videos anymore). The reasons are both technical and license-related. The solution above should work.
There is no longer a .opera folder in your home directory, the .opera folder was used by Opera 12 and earlier. (Of course, you could have one left over from Opera 12, but current versions of Opera do not use it.)
If you aren't still using Opera 12 or earlier, you could just delete your .opera folder entirely.
Cookies are there - if you're logged in here they are even enabled (well, for this site anyway). I'm on my tablet right now and can't look at the desktop settings, but it should be in the "Privacy and security" settings. Generally, Google sites don't like it if you disable third-party cookies ... and some ad-blocking extensions have also been known to block cookies from Google.
@roleen0317
no, this is not part of Opera bookmarks manager (from speed dial page)
it's independent extension that deals with bookmarks in sidepanel
on options page (of the extension) there is a button for export bookmarks (and also to export it with favicons)
for import you can use native Opera feature from O button - more tools....
I solved it by making sure the "adjust for slower websites" is not ticked in browser settings. I then rebooted and it seems to be working fine. I'm running Mint 17.1 KDE.
Settings > Browser, scroll down to the "Advanced settings", and tick the checkbox on the left of the "Show >advanced settings", then under the "System", untick the checkbox on the left of the "Use hardware acceleration >when available", and restart the Opera.
The above solution works fine.
Thanks for your help.
OK. Gave it another shot. It is now working; the latest peppperflashplugin-nonfree is now installed; video is working as expected. Tested it on various sites. I am now a happy camper again. Thanks for the helping hand much appreciated.
..In addition to previous post, following conditions are needed to trigger the issue:
Opera need to be positioned near the right edge of a monitor with high resolution (4K or QHD) with a low resolution secondary display (ordinary HD).
I tested two different systems, 4K and QHD: 3840 pixels wide and 2560 pixels wide both trigger it in a dual screen setup with a normal "HD/1920" secondary.
vux777, thanks for the reply. I'll experiment with that flag.
I wish I could mark this as solved since after closing the "...all of your devices" dialog in the bookmarks window, I can drag and drop as you say. At first I simply ignored it because I don't have any devices 🙂