I hate it when this happens and has happened many times before.
I had probably more than 20 Firefox browser windows on YouTube open and then I got an "Out of virtual memory" error and Firefox crashed.
I lost all the YouTube windows that I had open.
Later, when I restarted Firefox a few times I got maybe most of the windows back, like always I am upset that I lost; Who knows how many of them?
Now I better hurry up and post the links of the ones that I recovered.
The best singer ever? I don't know! Maybe "Frank Sinatra".
There is a change of volume from some songs to others; Very bothersome!