The Blues Scale 2
So the blues scale is a Jazz based Minor Key construct
and has nothing to do with true blues music at all.
True blues has an underlying Major sound and is hardly ever truly in a minor key
The Kings Of Lounge play an instrumental version of Sunny Goodge Street by Donovan, referred to at the end of The Blues Scale Explained part 2 video, this piece uses the Blues Scale exclusively for the main melody.
It is in the key of B minor
This Is The Blues Scale