Watch the Sub V7 for VII Minor 7(Flat 5) online guitar lesson by Robbie Calvo from The Modal Alchemist
In this section I'm using an E9 arpeggio to improvise over the G# minor 7 (b5) chord vamp.
You'll notice that the backing track is very moody and dissonant; this is because the minor 7(b5) chord doesn't function as a resolution point. When I played over the track I was listening to the feel and mood of the music and I really tried to be sympathetic to what the harmony was telling me I should play melodically. I totally advocate listening to the backing track first before diving in and taking a shot at a solo. Get the vibe in your head first, and then go for a take.