I answered my own question eventually: The DVD-RAM discs (3) supplied with the machine are not designed to be finalised - and cannot be finalised, but they may or may not play on other equipment. I have bought DVD-RW discs since, which are also editable, and can be finalised, and will play on my computer and on my other dvd player. Hope this information is useful. AG.
Anthony Gask, December 2007