This short tutorial by user David Schlachter will show you how to set up your webcam to work with web browsers on the FreeBSD operating system, namely Chrome/Chromium or Firefox. See the link below for the full set of instructions (it’s very short)

First, install webcamd, e.g. using pkg install webcamd. Load it at boot by adding the following line to /etc/rc.confwebcamd_enable="YES". If you have multiple webcams on your system (e.g. visible light and IR), you’ll have to add a line specifying the location of each camera on the USB bus, e.g. webcamd_0_flags="-d ugen0.6" in my case (see man 8 webcamd and man 8 usbconfig). You’ll also need to load the cuse kernel module, which you can do at boot by adding cuse_load="YES" to /boot/loader.conf.

Using a webcam on FreeBSD in web browsers: https://www.davidschlachter.com/misc/freebsd-webcam-browser