In opera://settings/?search=flash, I chose "Block sites from running Flash" have disabled all Flash, and there is no exceptions. So why are Flash videos not blocked? What's more, some even automatically start playing.
Example URL: http://time.com/4711263/justice-league-trailer/
Also, I have other changes in the Settings.
1) I have Turbo turned on
2) I have all images turned off.
Version: 45.0.2552.812 - Opera is up to date
Update stream: Stable
System: Linux Mint 18.1 (x86_64; XFCE)
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36 OPR/45.0.2552.812
Welcome to Opera's Forums @Highpitch!
Actually I don't have Flash Player installed and those videos are auto playing, they are HTML5 so you should install this Disable HTML5 Autoplay extension.