Moose himself says they're pretty basic "generally pretty good" build orders, rather than necessarily being totally optimised expert options. This is probably extra true since this vid came out before the latest patch.
So today there are two versions on Steam. The "Extended Edition" which came out in 2014, and "Retold" which came out two weeks ago.
EE was basically just the same as the original CD version from 2002, except altered to support modern screen resolutions, and then they added some new balance patches and a Chinese civ which were extremely poorly received for a whole bunch of reasons.
Retold looks much, much better with proper newly-crafted models and textures. It took out the worst of the patches from EE and the Chinese (with a promise that the first expansion will be an "all-new" Chinese civ). It's also got a heap of design changes which have mostly been regarded as positive: god powers are reusable for a Favor cost (with Atlanteans balanced by their Favor cost to reuse being much lower than other civs), the house limit is raised so you can build bigger armies, and the UX is enhanced with better hotkey support, among other things. It also has good multiplayer servers, rather than being peer-to-peer, so lag is vastly reduced.
Yeah part of the problem with EE was that even if you didn't buy Tales of the Dragon, the patch they released alongside it added a bunch of unwanted stuff. Giving the Greek civs a mobile healer, the Norse an archer, Egyptians a Classical Age specialist raiding unit, and Atlanteans a long-ranged siege weapon. All of those got removed in Retold.
Weren't those part of the Titans Expansion on first release?
I thought I remembered the flying healer along with Hippocrates and catapult/ballista for Atlantis at least, if not the Norse and Egyptian units
Edit: just looked it up on the wiki and those were all new. Probably why the campaign was a little easier than I remember when playing AoM 20 years ago lol
The flying healer (Caladria) was an Atlantean unit, and the catapult (Petrobolos) is Greek. Hippocrates was the new Greek unit and Onager for Atlanteans, which is more of an anti-building siege unit. It can be a bit confusing because in the original game's campaign, the "Atlantean" nation was represented by the Greek civ. And the Atlantean civ did get the Cheiroballista which is a counter-infantry unit technically classified as siege.