Bullet, thanks for your continued thought on this. Your mate come up smelling of roses with the suggestion of http://www.snapfiles.com/get/avicodec.html
This showed that the required audio codec was not installed. It wanted an audio codec called ACELP. A quick google search came up with www.acelp.net,
where there is a free download for a 32 and 64 bit version. The site seems to specialise in codecs for speech and the mobile phone market.
So I can now watch and listen to the cyberdog tutorials on my 64 bit Win7, Yeh!! One word of warning however, this only seems to play on Windows own media player...VLC still reports a missing codec.
Out of interest, yesterday I opened up the first video in my wifes ancient non intel/AMD chip powered laptop of a great age...the process of burning to a cd-rom in a different format took more than 4 hours! it was encoding it about 1/8 speed of real time playback!.....and I still would not work back on my PC.
Thank you for your work, Sherlock!