Besides, I had to replace libffmpeg.so becuase youtube said, my Opera didn't support h.264, so I downloaded opera-ffmpeg-codecs-58.0.3029.81-1-x86_64.pkg.tar.xz from repo.herecura.eu/herecura/x86_64/... and now everything is all right!

Ok, I added libpepflashplayer.so to /usr/lib/adobe-flashplugin as well.

jimunderscorep, thank you very much! I added my route to pepper_flash_config.json and deleted others. It helped me!

I use Opera-stable 45.0.2552.812, Debian GNU/Linux 8 (jessie) (x86_64; GNOME)
I have added file libpepflashplayer.so (25.0.0.171) into /usr/lib/opera/plugins
I have cleaned cache, cookies and restarted Opera, but I get Adobe Flash out of date!
How can I fix it?