The following is not exclusive to Ubuntu. It probably works on any Linux.

As many of you know, I am an ENT surgeon by profession, and also a tech enthusiast. As part of my trade, I need to do endoscopy of the nose and throat, and also record and give reports to patients. For this, I use a cheap AV to USB recording device, called EasyCap. For Windows, it comes with a recording software, called Honestech. However. for Linux. one can simply use vlc for recording.

Install vlc:

sudo apt install vlc

For recording, the steps include:

Install vlc.
Open vlc
Open Network Stream:
Video device name: /dev/video2

In View

You may need to change and try the various available video devices. One of them will be your webcam, and the other, the AV to USB device.

If the color saturation bothers you, install v4l2ucp.

It is not normally available for Ubuntu 20+, but you can install it like below:

Download the deb from here

First install qt4:

sudo add-apt-repository ppa:rock-core/qt4
sudo apt-get update
sudo apt-get install libqtcore4
sudo dpkg -i ~/Downloads/v4l2ucp_2.0.2-4build1_amd64.deb
sudo apt-get install -f

You can experiment with color settings by loading v4l2ucp