OOPS! My mistake!
I had open the directory that I had created called "gnash_media", and nothing appeared in that.
BUT
I later found that there was a SECOND directory "gnash_media" (one of them must have one or more unprintable characters in it, somehow), that had several files, including one called "videoplayback", which was about 25MB in size.
When played in SMPlayer, the picture hardly moved (more of a slideshow), and there was sometimes
a hiccough in the audio, but these issues may well be because I have only 256MB of RAM, and was doing
other things at the time. I'll try other playback tools, will convert to audio only, and have ordered RAM.
I think probably my problem is solved.
Thank you for your help.
-Scott
Curiously, it doesn't seem to remove any files after the page is left or even the site YouTube is left.
There seem to be lots of small .jpg files and empty files named s0 s1 s2 and so forth.
I'll have to be diligent about cleaning everything out after I've finished with it...