The recording I heard first was a different YouTube post. It's at http://www.youtube.com/watch?v=UhGBZdjxe21 and posted by "bronzemom". [I'm not sure how to transfer it here via a "blue clicky" as Leadfingers has done.] It's the same song -- and, yes, it's plural, Sarks, not Sark.
The video posting by Leadfingers shows the Corries playing and singing, while the other has a series of fine pictures of Scottish scenes, etc. I can actually understand more of the words of the "bronzemom" version than I can on the one posted above, but still need help.Hope someone can come up with the lyrics.