Is this a legit scale though? To me this just sounds like you've added a chromatic approach note to the III. You could take the same scale (HM5) and add a chromatic approach note between the I and the VII when descending. Does this create a new scale as well in your opinion? This seems overly complicated to me.Don‘t forget the Spanish-Phrygian 8-note scale in that context: a mix of the fifth mode of harmonic minor and Phrygian (fifth mode of natural minor).
Different from half tone/wholetone and altered (seventh mode of melodic minor).
Regarding the video (which I haven't watched lol): there's another way to get that 13b9 sound without having to use the diminished scale (but still using the scalar approach): it's myxo b9, the 5th mode of harmonic major.