Marcel: that's a Javascript problem. Simply click on the "No longer available" link and it should land you on the Youtube page with the video (at least it worked for me).
François: interesting video. I've seen people do it a few times. However, I'm not 100% convinced that this is the way to go for the following reason: felt as well as wool tends to shed fibres. I'm sure that in the long term those fibres will collect somewhere, probably on the lens or in the shutter mechanism. There's other very durable material e. g. "cell caoutchouc" (that's the German term directly translated; it doesn't translate very well. It's used as a sealant for windows and comes on rolls of 1mm to 3mm thickness with an adhesive on one side) which doesn't dissolve or disintegrate easily. Yes, you might have to replace it after a decade but I still think that it should work really well and it should be more durable than the original light seals. This "felt and wool" method is still "new" in a way. It still needs to prove that it actually lasts more than a decade.
EDIT: the stuff I was trying to translate sometimes goes under the name "foam tape" and also under the name "neoprene foam tape".
