This is an incredible exercise that will really help you develop the ability to take solos and hear the movement between chord changes. Since I’m not completely happy with how I explained it in the video, here is a breakdown of how works:
First, figure out the correct scale to use over each chord in the song. For minor 7 chords, the scale will be the Dorian scale of that key (for example, if you have an F minor chord, the scale will be F Dorian).
Play through the song slowly with a metronome and play each scale starting from the root, or the first note. For steps 1-4, keep a steady stream of 8th notes without stopping.
Once you have mastered step 2, you must begin connecting the scales without starting on the first note at each chord. Ex. You have 2 measures, the first one being an F minor chord, and the second one being a Bb minor chord. For the first measure, you play an F Dorian scale. However, when you reach the 2nd measure, don’t jump and start by playing a Bb, play the next closest note that is in the Bb Dorian scale.
After being comfortable with fluidly moving between scales, you may start skipping notes in the scales so that you are playing larger intervals.
Finally, you can begin rhythmically leaving notes out so that you are not simply playing a stream of 8th notes. You may also begin adding chromatic notes, or leading tones.
This may seem a little complicated, so when I have some free time, I may make a new video that answers any questions that might arise.