I cn install Camd library and get Hd-Rec to lpad, but this far none of the USB midi devices I've tested were properly handled by MorphOS.
Which model did you use?
P.s. Have not been able to watch your video yet, bandwidth is too lOw here.
I use simple, cheap USB2MIDI cable off ebay for $5. It has MIDI in and out. I installed the CAMD library, set the synth to be controlled by external sequencer and then all the tools included with camd worked. Even the simple MIDI player I downloaded from OS4Depot written in Blitz BASIC works. Horny works too. MIDI works nice on my Amiga.
On this video the sound from the synth is too loud and little distorted. I learned my lesson and in my newer videos I set it to be on lower volume.
One of the utilities included with CAMD library shows the keys pressed on the synth, or the sequences send to the synth - something like the old EDPlayer on classic Amigas. Very useful and helping for learning songs and performances.
Pure asynchronous play.