This is a great 'outside' sounding lick that uses the half-whole diminished scale to take you from the I chord to the IV chord in a blues. In this case it's going from a Bb7 to an Eb7. If you're unsure what we mean by I and IV check out our Theory Lab course to get a better understanding.
This is a scale that's built by simply alternating half-steps and whole-steps and you move up the scale. We can think about it as starting on the Bb, which is root. This scale has a very tense sound, but as we're playing over a Bb7 we end up playing a semitone away from a chord tone, then straight back into a chord tone. This gives a contant tension followed by immediate release! Dion then skilfully uses a chromatic run to get himself into an Eb7 arpeggio to perfectly outline the IV chord in the second bar to give us that sweet sweet resolution!
In the video Dion plays this at high speed and makes it look easy! Don't expect to be matching that tempo to begin with - take it really slow to begin with and watch your timing! Try to use your little finger to to reach the notes more comfortably, and above all have fun! Here's the tab: