I've scoured the All-Knowing 'Net for this answer, but haven't managed to find the answer. I have found statements where Plays.tv "can be used with any windows game" but haven't found an explanation on how to set them up.
Microsoft Flight Sim X is a particularly difficult game we had issues with when it came to hooking for encoding. Currently it seems we have it disabled due to issues found when testing it. Oddly enough the Steam version seems to be enabled. I'd have to check with the department to see if that was an oversight, or if the Steam version actually is okay.
I'm having the same issue. It does not work for me on FSX Steam Edition. It works great for American and European Truck simulators but will not record FSX.