Please check following points:
The video output resolution is set correctly in connected source’s video output settings. If it’s not set correctly there is a chance that video won’t be displayed in software preview window and there won’t be signal on pass-thru either. Please check output resolution of your game console/camera once again.
In case the video can be received in RECentral 3 and other supported software but there is no video on pass thru: from Live Gamer HD 2 HDMI out to TV/monitor please try following steps: