Cool, I watched that. Here's what I learned (some of this is in the other threads, I'm sure):
3 new campaigns: Orcs of the Marsh, Defender of the Crown, Champion Arena
Also, I saw that Armored Princess itself seems to be one of the options from the splash screen, so it's basically an expansion for Armored Princess.
Orcs of the Marsh is basically a mod for the Armored Princess campaign. It's probably the Gift Bag and a few other things besides. Not sure if I can really be bothered playing through this again - it depends how different it is.
Defender of the Crown - a small campaign (6-8 hours) with randomised enemies. In this video we can see some sort of tower that spawns enemies etc. Sounds promising and looks like it will have good replay value, which is very important for us King's Bounty veterans.
Champion Arena - another small campaign that is based around 9 boss battles, the 9 bosses being those from The Legend and Armored Princess. Plus, and this is what I really like, you join a guild which restricts you to a certain race of units (elf, demon etc). This is similar to what fans were calling for after The Legend and especially the Arena battles in that game. If you play the Bounty Hunter faction you'll do lots of side quests as well. This sounds good too.
And of course the editor, which we don't know a great deal about yet.
AND, it looks like the Spirit of Rage abilities from The Legend are now spells in Crossworlds. So basically it's more of everything, all packed into the same games, with what will hopefully be a very powerful editor.
So it looks like I'm going to be playing King's Bounty for years yet.