These cascading descending double stops make use of hybrid picking ( pick and fingers). These are phrases or riffs that can be used to play over the V to the I chord. These also make use of the open 1st string E as a pedal point or drone note. This style is used a lot in country style guitar or chicken picking but does not need to be limited to just that. Three different keys are used here - C major, G major and F major. So these phrases can be played over two measures of G7 to C, D7 to G and C7 to F. Lotsa fun and sounds pretty slick once you get it down. So click on the links to check out the PDF's and the video.