Maybe I missed this in the video -- a blue arrow indicates a weak cadential relationship, and a yellow arrow indicates a strong cadential relationship? (Is this correct?)
Hex means a scale that is bi-triadic hexatonic, meaning a scale with 6 notes made out of 2 non-overlapping triads. So, a Hex IV Vm is a scale you get by using the notes from the major triad on the 4th degree plus the minor triad on the 5th degree. For example C Hex IV Vm is , F A C - G Bb D so, C D F G A Bb.
