Re: How do I get 23.976Hz?
I worked around the xv issue by using gl output with -framedrop and -autosync n, n > 0 to prevent audio sync drift and weird occasional tearing at the top of the screen. I've not done through testing on the autosync parameter but a value of 2 seems to work fine.
All that's left to fix is getting the exact refresh rate on a secondary monitor. (Anyone?)