If you want to use CamTwist with OBS, you have to use the CamTwist 3 beta. CamTwist 2.5 is a 32bit application, so it won't work with OBS.
As for Window capture, it should be available in the next release. Until then, if you don't want to use CamTwist, you can try fullscreening your PVR window and capturing that wind Monitor capture.