It's possible you have tried this, but just in case, you have a DIGITECH Audio Visual Composite AV to USB video recorder that you want to use with your security camera to watch it on your main screen, it is possible this could be useful to show you how you can set it up:
First of all, the Power Connection:
You must connect the 5VDC power supply to the micro USB port on the video recorder and then plug the USB A connector into a USB power source.
Then you must configure the Video Input:
Connect your security camera's Composite AV (CVBS RCA x 3) output to the corresponding input ports on the video recorder.
Make sure the camera output is set to NTSC.
It's time for the Video Output:
You need to connect the HDMI standard out port of the video recorder to an available HDMI input on your TV.
Motion Detection:
Check the video recorder's settings for motion detection. If your camera doesn't have built-in motion detection, the recorder might have its own feature.
Refer to the lost instructions or you can contact DIGITECH support to get a copy of the manual.
You finished with the SOFT, now its time to the HARD...ware
Software Configuration with Xeoma:
Ensure your video recorder is connected to your computer via USB.
Open Xeoma on your computer.
In Xeoma, add a new camera or select an existing one.
Choose the appropriate source/input. In this case, it would be the USB input from your video recorder.
Configure the settings in Xeoma, including motion detection if available.
Now you gonna view on TV:
Turn on your TV and select the HDMI input to which the video recorder is connected.
You should now be able to view the live feed from your security camera on the TV.
n.b.- If you encounter issues, refer to the product manual (your wrote that u lost it, try to search on the net) or contact DIGITECH support for assistance.
This is only a suggestion, I'm not an expert with this, so it is possible other puppy user will give u a better and more correct explanation, so consider this as "the last resource"
Have a nice day.