It's great in the sense that it gives us a good idea of the way the aircraft sounds, but the audio is of too low a quality for any of us to make proper use of it, I'm afraid.
Though I'm sure I can find some good recordings of a Spandau *somewhere*. As for the rotary engines, I can't say. I'll probably have to fly to Holland and record them myself, like the author of those videos suggested to another viewer.
