Tooltips. All the tooltips!
-- Really, though, without wasting excessive time(people can pause the youtube video later), try to mouse over(a full tooltip, not a passover blink, please!) as much as is reasonably possible. Loadouts, Structures(City Buildings and Map), Unit Traits, Unit Mods, Techs, and so on and so forth.
We're fine with typos, as I would like to think that most of is know it's one of the last things that gets fixed, due to translation work anyway.
-- Otherwise, I mostly am in line with Fluksen and Gloweye, especially Fluksen's point about playing Syndicate/Assembly, if feasible. I mostly just want to see something other than Vanguard/Promethean which has been the headliner most of the time so far. If Vanguard is to be the one played, please at least run with a different Secret Tech, after a quick review of all of them. Perhaps even let the chat run a quick vote to pick for you.
-- As for something not mentioned so far, I would hope we can see how the Doctrines system works, as it seems to replace potentially both Empire Upgrades and Global Enchantments. We know there are limited slots, we know you have more choices than slots(especially with owning Landmarks), but we don't know about costs, or implementation of activating and deactivating them. Let alone their effects.
-- Perhaps most importantly, though...
Go wild! Try out unusual combinations of Units and Mods. Show off different unit abilities, both friend and foe. Don't play for optimization, but for fun, for yourself and the viewers. Maybe it would normally be better to befriend that NPC-Faction, but if you do, we might not see that side of Diplomacy, or the weird abilities of their units in combat(if not encountered yet on the map). Of course, this is mostly in juxtaposition with also befriending a different one, so we do get to see that process.