The link below is to a BBC radio broadcast about the ancient Welsh Tradition of PLYGAIN singing (PLUG-EYE-NN)
http://www.bbc.co.uk/programmes/b00pdkw1 (you may have to copy & paste)
It will only work on the 29 Dec 2009.
By the time you read this the above link may already have become unusable because of multiple programme makers each having a share of the programme.
This programme went out on radio before we were able to know about it - but we just mangaged to catch it before it disappeared for this year.