This is quite a common exercise, but a really good one, I must say. It starts with playing a C major scale 2nd string, from the top C (13 fret) down to the same note one octave lower (1st fret). Play note the first note and try and replicate that sound by bending up the next note in the scale. So if I start with C (13 fret) I will have to bend the B (12 fret) up a half step trying to match the fist note I played. And so on down the scale, like I do in the video.