A happy and unexpected upshot of the technical difficulties – the Youtube playlists now function as intended, no longer beginning with the second video in the sequence! (At least on these two WP sites.) So I shall now go back and embed the playlists in the entries as I had wanted to do from the start.
Postscript. I see that in some cases the Youtube video player cannot play when placed in such a narrow space – so it says. Another query for the technical support staff; in the meantime, in those cases where it does not fit and doesn’t work, the playlists or parts thereof can be watched on the Youtube channel or over at Musicuratum LP: Large Print.
Where would we be without the little quirks of all the computers?