On Jun 9, 3:21*pm, "GB" wrote:
http://uk.video.yahoo.com/stupidvide...ideos-24317891...

--
Murphy's ultimate law is that if something that could go wrong doesn't, *it
turns out that it would have been better if it had gone wrong.

Faulty tap washer.
The note was changing as the valve was moved. Caused by the
obturating disk vibrating/chattering on the valve seat.
Fairly common.