Using webcam is a common thing to do on a laptop and it is not hard to set up in FreeBSD as well.

First go ahead and install webcamd,

$ doas pkg install webcamd

According to the man page, webcamd is a daemon that provides access to webcam devices and such. According to the man pages, we need to load the cuse kernel module as well as start the webcamd daemon.

# Adding cuse to bootloader and webcamd to start up services
$ doas echo 'cuse_load="YES"' >> /boot/loader.conf
$ doas sysrc webcamd_enable="YES"

To load the kernel modules and the webcamd service without reboot, you can do the following,

$ doas kldload cuse
$ doas service webcamd start

After which, you can go online with your Firefox and do a webcam test online. I am relatively surprised as how easy it is to set up webcam support on my FreeBSD. A shoutout to this David Schlachter's page for providing me the initial steps to setting up webcam on FreeBSD.