Here are ten seconds of behind-the-scenes views beginning at 1:32 of a couple of '41's with the Kingston Trio.

http://www.youtube.com/watch?v=3AUZEdFeVwU&feature=player_embedded

Too bad somebody got the aspect ratio wrong along the way somewhere.

Pete

Here's another one with a brief shot of a TK41, the commercial is pretty good too.

http://www.youtube.com/watch?v=leSXp0XPd7U&feature=channel

A push-pull on-off switch, will the modern miracles never cease?!! :D

Great footage, thanks for sharing it. I have some Andy Williams Show music clips from the mid 60s and in a few of them the TK-41s are evident. Also in this Sly & The Family Stone performance http://www.youtube.com/watch?v=Lrt2RAnOyBo one of the TK-41s can be seen from a distance in the distant shots, at 4:52 it can be just seen below the timecode.

Here's a shot of TK-41s in action (obviously Burbank), in an ad for southern California travel.

Now, can anyone identify the show?

Edit - the ad is from December 1965