My system just installed the January 2019 Windows 1809 update and the problem affecting Opera seems to have gone away. Thanks, Bill Gates. I think I'll stick with Firefox for a while. Maybe permanently, with all the new bookmarks I've made. And the program handling. Entering this with Opera, by the by.

@quicksite For a few years Opera was a completely new and independent paradigm. They were designing and upgrading their own brand new type of browser from scratch. All was well and impressive and I loved it, until something happened. I don't know exactly what, maybe the 2008 economy or or the conservatives tossing out the socialists (again) but the original beautiful and new and unique browser was replaced by yet another Chromium mod. I got mad and quit for a bit but none of the others could quite do what Opera (even then) could do so I went back and was happy once I got used to it. It's better than Chromium in many ways and way better than Chrome. And, of course, anything is better than Edge. But I think MS has been futzing around with the allowables and detrimentals and making it difficult for anybody who doesn't have a company address at 1 Microsoft Way. Google have been doing the same thing to MS. You know, it just occurs to me, all these corporations throwing temper tantrums at each other with us people like little pavement ants at their feet, doesn't it seem as if Attack On Titan! is really a metaphor for living in the modern corporate world? Anyway, Opera is Chromium, Chrome Does Evil, Edge is IE in a Big Brother sort of way, and Safari is connected with those people. Firefox might be the only truly independent browser left out there. Maybe Konqueror in BSD. Unless you want to fire up a DOS machine and use Lynx. I think that could still work.

I have gone back to using Firefox64 as my default browser because Opera has been running like a grandma at church bingo since the December 2018 Windows 10 update. I have tried reinstalling Opera after completely cleaning out anything Opera related including from the registry. I have disabled Internet Explorer. I have tried running with no bookmarks or extensions. I have disabled QoS Packet Scheduler. I have disabled hardware acceleration. I have tried with and without VPN. My Internet access speed is consistently 100+mb/s down and 35+mb/s up with a ping of less than 20ms. Still, since the beginning of the month, some web sites either slow to a crawl and end up in bits and pieces or never arrive at all in Opera. For example, PrePal pops right up while Newegg barely makes it. I am entering this post from Firefox because Opera cannot open up the Opera web site at all (isn't it ironic?) I have tried dozens of times. I will continue looking into the problem but until some lasting solution appears I am going to be using Firefox.

@lelivienne I have not seen any AliExpress nags in my computer. Try deleting all cookies that have "aliexpress" in them. Or even "ali-" anything, if you're careful. And completely clear the cache back to forever. Also search your C drive, including hidden and system folders, for anything related to AliExpress and uninstall or delete it.

My computer, a high end MSI laptop running Windows 10 x64, has been crashing to blue screen a couple of times each week at least, and every single time it occurs when I am entering text into Opera. Whether in the address bar or a comment area makes no difference. As I am typing, the computer will suddenly drop to a blue screen that says "Oops, your computer encountered a problem and needs to restart..." There is no indication of the nature of the problem, nor is there any memory dump, even if memory dumps were readable outside of Redmond. It never happens outside of Opera. Any ideas? Thanks for your time.

Actually... the problem stopped right after I posted that it was a problem. Two weeks of occasional green videos, and then it just stops. AVC1/MP4a videos are appearing as normal as the Opus ones. Go figure.

PS-- I watched five year old video that has the AVC1/MPG4a and it came up green. Unless Youtube has recently recoded all their videos, the problem is probably due to a recent change in Opera's codec handling.
https://www.youtube.com/watch?v=J41qaxTi6mg

(Would be nice if previous forum entries could be edited after posting, rather than having to reply to my own post just to add something.)

Recently a few Youtube videos have been showing up with the video all green. Audio is OK but the picture cannot be seen. According to the Stats for Nerds, the green videos are using AVC1/MPG4a codec. Videos for which the picture shows up normal are using VP9/Opus codec. As this is a recent phenomenon it may be the latest version of Opera either lost compatibility with the problem codecs, or the codecs were changed and they lost compatibility with Opera. I checked the same videos in Edge and Chromium and they all appear fine, no green screen.
Two examples of green video in opera are:
https://www.youtube.com/watch?v=6no3wayoPS0
https://www.youtube.com/watch?v=79VdrbafeJA
Two examples of similarly themed videos that appear properly are:
https://www.youtube.com/watch?v=wYWgchNrqOU
https://www.youtube.com/watch?v=BHOmek4OC0o
I suggest you check the Stats for Nerds for these to confirm that the codecs appear to be the common factor.

Snapshot already pops up a file requester when Capture is selected, but it always defaults to the Desktop. Opera needs a setting for default saving of the Snapshot captures so that the inconvenient and time wasting file requester does not appear if it is not wanted. Opera developers, are you reading?

@nvmjustagirl
If one selects "Ask" then every single download involves a popup. The problem is occurring only with Snapshot, and that tool already pops up a file requester when selecting Capture. The solution would be to either connect Snapshot to the default download location or to add a setting to permanently select the Snapshot default Save location. Your solution is not a solution