I thought this was an interesting effect. It sounds like a 12 string Rick being strummed or finger picked in the background at a low level in the first video.
The Vejtables - Shadows
https://www.youtube.com/watch?v=wN7n3qdYX1k
More Vejtables
Two Rickenbackers!
Vejtables - I Still Love You.mpg
https://www.youtube.com/watch?v=YdToSxH1KtY
The Vejtables - Hide Yourself (1966)
https://www.youtube.com/watch?v=_HQGl8OidQ0
