The DNS ‘magic’ is basically a bash script which uploads the TinyDNS files to the Bytemark ‘Legacy’ DNS server - this then serves them, (assuming you’re the first one to upload records for that domain). Most of the magic there is running on the far end.
There’s not (yet) an equivalent for Mythic Beasts, but it’s being worked toward at the moment, with the integration of OctoDNS, which supports Mythic as well as other DNS providers.
For now, you’ll need to update the DNS manually via the relevant control panel.