Sigur Rós sound-a-likes: homage or fromage?

The IPKat confesses, in at least one of his incarnations, to being a big fan of the Icelandic group Sigur Rós, and keeps up to date from time to time with what they are doing via their website "eighteen seconds before sunrise".  A recent article on the website amused and intrigued him.  If you are also a fan of the group, you might find the music accompanying the advertisements in the videos below strangely familiar. The IPKat will leave his readers to reach their own conclusions, and would be interested to see what they think.