The red LED indicates that the RPi is actively using the camera. It lights when you are using raspivid, raspistill, etc., and is otherwise off. When pivideo reports “Raspberry Pi Camera port is not active” it just means that no program is using the camera. In your case, it means that raspivid has exited.
Mode 5 video is either 720p or the special case of lowered resolution 1080i video. You can also tell the detected resolution by looking at the four green LEDs on PiCapture. Please be sure that the mode you are specifying with raspivid matches the detected mode.