"Alan Erskine" wrote in news:C1qBj.24401
:

Was the green glow ionisation caused by speed or was it OMS/thrusters?

OMS and APU exhaust, my guess. The catalyzsed hydrazine used to drive
the APUs contains unburned ammonia and hydrogen; perhaps it's burning
externally for a while, but not above the lower atmosphere.

I think this is the first video of a totally dark night launch I've
seen, and I can only guess at some of the visible events. It was
very interesting!

--Damon