The record video out would behave the same as the monitor out except for the omission of OSD overlays, so when video 4 was active (and the pre-amp outputs were getting the audio from video 4) the record out would get video 4's video signal (as well as stereo analog audio, but I'm assuming that in this scenario we'd be leaving that unhooked). I haven't tried hooking the record video out up to a display and monitoring it on different inputs - have you verified that it cuts off when video 1 is active?