If you’re talking about alias lists (I’m on my phone and can’t watch the video) then they’re made by periodically resolving the domain name and generating a list of IPs for the firewall. So there are a bunch of reliability problems with that.
The first thing I would suggest doing is making sure that your client devices are using the dns resolver built in to pfsense, and also make sure the dns cache and the alias lookup period are the same, that way when a client requests an address from the dns resolver it should pull the same ip from its cache that the alias list is using, this will help with servers which resolve to multiple IP addresses.
The other thing is you need to make sure you have the FQDN of every server that whatever it is you’re doing tries to connect to. It has to be the absolute address because it resolves to an IP, so a domain name will not work.
And even then its going to struggle with anything weird or CDNs.