Watching this RUSH DVD last night and especially enjoying the cover songs.
The explanation is a few songs that impressed them while growing up in rock bands, the very best of which, IMHO, is Summertime Blues done a la Blue Cheer.

Who here is old enough to remember rocking out to Blue Cheer ?

They were an awesome power trio so, this version is perfect for RUSH to cover..........and they do a tremendous job of it.

The PCM stereo audio is superior to the 5.1 on this disc, BTW, for those of you that can enjoy either.