That was very useful! It is kick-started me. Firstly, I was ignorant about flv, so that was very useful.
Your post has led me, by various routes, to discover that wmv is not only an export option for Impress,but also can be imported into more recent Windows PowerPoint and is also acceptable to DVDstyler, but not to Devede.
I hope that when I try this, it will all work!
Very many thanks. I will let you know in asap.