I know that @Pedro was looking into better playback options for WCP DVD video in the GL enhancements. I don't think this was completed but I may be wrong.And as usual in these cases, after several hours of experimentation and cursing, a solution of sorts presents itself just minutes after one admits defeat and asks for help.
This is not a real solution per se, but rather some information that might be useful:
The WCP DVD playback addon does not, it seems, like external screens on laptops. The fact that the laptop has multiple GPUs may or may not be relevant.
Literally every other piece of software or game I have ever tried have worked flawlessly whether on the internal screen or on any of my two external ones. But not WCP. If I want to see the DVD movies, I will have to make the internal laptop screen my primary, then launch Prophecy so it shows up on that screen an no other. Then I get to see Tom Wilson be an asshole and all is well. I'd much rather see him on my 27" screen, but oh well.
I'll continue experimenting; if anyone has any idea on how to make the vobs work on an external screen connected to a dual-gpu laptop I'd be grateful if they shared.
You’re right, I got distracted by other things as i had stopped hearing about issues with movie playback.