Edit: Since the below was written, I've figured out how to weave in several video streams into one whole.
Trying out new video editing software -- Nero 10 Multi-Media Suite -- and, though I can paste the mixed audio onto one video track, I can't seem to figure out how to edit several video streams showing each instrument being played together within the same video. Anyone have proficiency with this and can offer some advice? In the meantime, here's the one-stream version ...