Opera standalone installation? No. I didn't and I won't.
It's a risk-free test and will tell you if it's something with your profile or not. It doesn't mess with your normal Opera installation and doesn't make changes to the registry etc. It's just a folder that you can delete after you're done test.
I think you've seen this on the internet, correct (https://forums.opera.com/topic/27385/message-this-site-can-t-be-reached-the-connection-was-reset)? It's the same page.
Okay. wanted to make sure.
Ctrl + Shift + i resulted in the image I'm uploading. Nothing has changed here. Should something happen?
In the Network tab in the developer tools, in the list of things that were fetched, at the top of the list, you should see "video-download-helper" of type "document". Select that entry and click "headers" to see Opera's request and the response from the server. It would be interesting to see all the headers. Be sure to hit ctrl + r after opening the Network tab and checking "disable" cache.
If you can't find the "video-download-helper" document entry, it probably means Opera didn't even get that far.