I had a problem being unable to watch the videos on this site - https://www.tvnz.co.nz/one-news/new-zealand
The images were on the player & the play arrow would light up when I hovered over it but the video wouldn't play. I tried a quick search on this forum but couldn't find anything helpful - quite often it's pretty hard to find simple, definitive answers in the Opera forums!
Anyway the way I fixed it instantly was to go to Settings (CTRL+F12)/Websites/Plug-ins (where I have "Click To Play" checked) and click on Manage Exceptions. Then insert the main site address (in this case https://www.tvnz.co.nz) and click on "Allow" as the option & then "Done". Voila! Videos now play! Hope this helps someone.
Using Opera v41.0.2353.56