It is the first time I have tried with this new computer but I have just checked with my old laptop where I used to have no problem, and it is the same there ‘An Error Has Occurred’.
I can still access all others’ videos on YT, and at least one SF member has reported being able to see mine, including the latest one.
This is it: Death of a Rat - YouTube
works for me on Linux ubuntu 98.0 using Firefox 98.0.
Have you tried different browsers perhaps and have you logged in to your YT account?
I have logged in to my YT account but I haven’t tried different browsers. But if it was something that I was doing differently with this new computer, why am I getting the same result on the laptop, on which it always worked before? And it is only my videos that I can’t see, all the others are ok as usual.
I wondered if it was because I now edit the various videos seperately (there are 5 here) and then stick them all together afterwards. Also I now get the editor to send the finished result to my computer and it is from there that I upload to YT. It seems quicker that way, but I have done that before on the laptop as well without any problems.
I’ve never performed that task tbh David, so can’t offer further suggestions other than a quick search on Google which has produced one suggestion…
there is also YT help…
All my videos are public, but I will look at that link shortly but at the moment I have one eye on the dogs at Crufts. 
Just had a look and it says video unavailable
It’s there alright David, but in a desperate bid to try again I deleted it and re-uploaded it. I can see it there but I can’t watch it.
I can’t watch any of my videos, even from several years ago, even though I can see them there. 
And just in case someone mentions (YT did) that it is because I have a new device, I can’t watch them on the old laptop, that I have been using for years, either.
Have you contacted YT support?
Yes several times, no humans are available but what there is keeps sending me round in circles. Everything suggested has been checked out. My new computer, my old computer, the Livebox, logged on, verified, the lot, all checked out and allow me to see any video I want with no restriction, except mine.
BTW Graham, I did watch the link you provided but it seems to be concentrating on the lack of videos showing, not ones that can be seen and not watched, and not by only one person, me. Your 2nd link is about people who restrict their videos, to a group or to anyone else, mine are plainly marked ‘public’.
ah! OK
Found this, what dom you think? I favour Method 2 for a start, but I hate to meddle with stuff I don’t understand.
I would say that number 3. is the quickest, and safest option to try first. You really can’t cause any damage at all by flushing the DNS cache.
Edit: When I try to play the death of a rat video it says ‘this video has been removed by the uploader’. I’ll try a few of your other videos.
This is the new link which leads me to the video, perhaps you were following the previous link to the one that I deleted.
I tried to see it just now and youtube says that you took it down.
I am watching it just now with no problem on both my phone’s.
Before I take any of the steps, and particularly the one you recommend @hairbear, does the fact that I have the same problem on my laptop too, so it isn’t confined to this machine, make any difference to your advice?
In other words the problem is confined to these 2 machines and as far as I know no others, (I think @david_gillies and @anon19463920 may have fallen foul of the gap between deleting and re-uploading), so does that make the Livebox the common denominator?
to add to the post by @griffin I can view it on my Linux (ubuntu) PC using Firefox with no issues as was the case earlier in the topic.
It sounds to me as if your account is the common factor. If you log out of your YouTube account can you see the videos?
No probs on my Samsung Tab 78 degrees F you have a very warm kitchen
I wouldn’t have a clue how to log out Brian, I always simply shut it down when I have finished, but in order to work out what you meant I first went to YT and put in the code for that video. And it worked, so I then came out and went back in and then went into my account and highlighted that video, and then others of mine at random, and they all now work.
Amazing. I have done none of the suggestions mentioned earlier and or anything else for that matter, just tried what I have done before without success. So a complete mystery, let’s hope whatever it was is now cured. We will see in the next few days. 
Thanks to all for the suggestions and offers of help. 