it was filmed during the recording of their album MIRROR which by the way goes out next month, it's been a year since they started their Youtube documentary series and it seems is going to continue into next year
btw every member of SCANDAL is going to have the lead vocal in at least 1 song! the last time that happened was in 2014 with their album "Hello World" (one of my favorite SCANDAL releases ever)
here is the release calendar