This is just a repetition of this thread:
https://forums.opera.com/post/63786
You have to judge for yourselves how important that is. It's not your fault, but the fault of the people making the sites.

I just realized I already posted that issue: https://github.com/honestbleeps/Reddit-Enhancement-Suite/issues/1863
I hope they fix it some time, but it seems that noone even looked at it.

Yeah, I would like to have this for individual sites, because I don't trust every single site with this, but it's actually a problem with the pages and not Opera. I'll try to get this to the right person. It's a bit difficult to find out where the problem lies because it happens when using reddit.com (page) with Reddit Enhancement Suite (extension) and the feature to convert gifs to webm. The site that does the converting is probably insecure, it seems. Now I only have to find out what site that is.

Since the developers already know of this problem I'll just wait for the stable Opera 28. Thank you.

Opera should have a setting to disable this warning. I know that the content I'm looking at is coming from an insecure site, but I trust that site. I can unblock it once, but I want to unblock it forever for specific pages. Please give us that option.

I have folders where I can put my bookmarks in, but is there a way to create folders inside of folders? Didn't find any so far. If not, please implement this in a future update. My bookmarks get really messy without subfolders.

Just tested it and it works. I remember a time some weeks before where YouTubes HTML5 player didn't work. Maybe it was a problem with YouTube and not Opera. Seems there was a problem with streamcloud. Thank you for the quick answer.
I just revisited the site were a video did not load and it was a flash video indeed, still wondering why that won't load.

I recently visited some sites that seemed to use HTML5 videos and they were not loading. One site, streamcloud.eu clearly said that I was using the HTML5 version of a video and it was not working. The flash version worked, of course.
Does Opera not support HTML5 videos? And, if not: When does the HTML5 support come? We're already at version 26 and in Chrome it works since I can remember it existed.