Hi

Just to be clear here on top of what Noel has told you.
If you downloads are in fact old BIAB mgu and sgu files they are indeed BIAB file types , but because of their age probably used BIAB midi styles. This is why you get the notice.
Quote:
“I've been interpreting the message as saying the song is a MIDI file.”

This it is not! it as above a Biab file.

A midi file will have a .mid file type and behave as Noel says.
Mike

Last edited by Mike Head; 11/14/18 11:35 AM.
BIAB2021 UltraPlus,AsusN55S1Tbssd, W10/64,Akai EIEpro
Yamaha CVP405,SquireStrat, CoolsoftVMidSynth
Novatation Impulse61 Ctr kbd, Cwalk blab Kontakt

http://mikesmusic.byethost16.com/