Hi rsberlo,
The VIXIA HF G70 is able to output video and audio through the HDMI port. There aren't any settings to enable the output. There are a couple of things to check if your computer is not receiving the output.
The first is to double check how you are connecting the camera. The HDMI should go from the camera, to a capture card, and then you would use capture software on your computer to send the video to your streaming service. The connection would not work if you are connecting the HDMI directly from the camera to the computer. We do not make capture software or capture cards through Canon, so there aren't specific capture cards or capture software we could recommend.
One other thing would be to try changing the HDMI Output resolution on the camera. Sometimes if the resolution doesn't match the settings of the device you are outputting to it can cause issues. To change the HDMI Output resolution go into the menu, go to the Display Setup section, select HDMI Max Resolution, and try a different resolution.
