It appears FreeBSD-13.0-RC1-amd64-dvd1.iso <https://download.freebsd.org/ftp/releases/ISO-IMAGES/13.0/FreeBSD-13.0-RC1-amd64-dvd1.iso> is too large to burn to disc. I have been trying with Cyber Power2Go under Windows 10, and k3b under FreeBSD 12.2 and Linux Mint 20.1 Cinnamon. Someone more knowledgeable than I should verify...