When I go to YouTube’s home page, then to a video, it works fine.
When I follow a link from elsewhere (usually an SDMB thread), sometimes it does not.
The “comments” section displays normally.
The “you might be interested in these other videos” section displays normally.
The sound works normally.
But the video itself just has a black screen.
When I use Microsoft Edge, it works fine.
When I use Google Chrome, it is hit or miss (usually miss).
Is there some setting I need to tweak?
Do you have an ad blocker installed? Dunno if this is your problem, but I had the same black, no video thing when I have AdBlock active. If I pause it, the video will play fine.
I don’t have any ad blockers.
A few possibilities:
Do you have any extensions installed? If so, try disabling them and see if that makes a difference.
Open an Incognito tab (Ctrl-Shift-“N”), which will launch without any extensions or other user customizations, and try it there. If that works, then it’s something you’ve configured that’s causing the problem.
Open the Chrome settings, open the ‘Advanced’ section, and scroll all the way to the bottom to find “Use hardware acceleration when available”. If that setting is enabled, disable it, and try again.
If any of the above solves your problem, I’ll send you a bill at my standard hourly rate, with the standard 4% “Doper discount” 
I’ve had that happen from time to time, too, and I don’t know why, but occasionally refreshing the browser fixes it.
If it’s an extension issue, this may fix the issue only if along with doing that you delete cookies.
I get a 400 Error once in a while because of a conflict with the Great Suspender extension. If I delete the cookies for the Great Suspender my issue is fixed until it happens again.
I’ve had issues in the past with YouTube in Chrome and this was how I fixed them.
I have this problem too sometimes. It seems random! I will just click on a related video then use the back button to take me back to the original video. It works every time.
It could be related to my extensions but they’re work related so they won’t be disabled any time soon. No ad blockers because they screw with my work scripts.
Seems to make the problem less frequent, but it still happens.
No luck.
Didn’t work this time.
Thank you all for your efforts.
Make sure when you delete cookies you select the time range to “all time.” I think the default is only for the last hour.
I thought I did. But, I tried again. This time, it seems to have worked! Thank you!
Am I going to have to clear cookies every time I want to watch a video?
No, just every time you have that issue. Or you can narrow down which extension is causing the issue and get rid of it.
I have an issue with the Great Suspender extension, but I don’t want to get rid of it. I also don’t like deleting all my cookies every time I have the issue, so I delete the specific cookies that cause the issue.
If you don’t want to delete all of your cookies when you have the issue, just delete YouTube cookies and you should be okay. If you don’t want to delete all of your YouTube cookies, you can narrow down the problematic cookies later as I did.
To just delete YouTube cookies do this:
Go to Settings > Advanced > Content settings > Cookies > See all cookies and site data
In the search box where it says Search cookies, type in youtube and now you can just delete the cookies associated with YouTube.
Thank you very much.