OK I'm listening now to Wes and I think I understand what's going on now.
I didn't realize this was possible, but it seems you can import .wav audio files into BIAB.
So you can take any commercial recording, import it into BIAB on its own track, and then
input the chords to the song, synced up to the temp of the audio.

So you can watch the chords go by as the music is playing.
I guess this could be useful to some people.

And you can also create your own tracks to input the solo and watch that notation too as the audio is playing.

A BIAB user for more than 30 years (if you can believe it) !