In the late 90s I sat in my studio one day and reversed engineered this production trick in Fatboy Slim's 'The Rockafeller Skank'. I'm explaining it to some students at dBs Music in 2013 but watching this video again, I haven't got it quite right. I've since realised the pitch bend messages to the Akai and Roland SE-50 should be independent, this allows the pitch shift to be automated back up to get that siren sound once the bend on the AKAI is at it's lowest point! The ability to invert the incoming MIDI signal to the SE-50 from - to + was a red herring on reflection! Enjoy!