I will give some general directions for what I think the next gameplay should be about:
1) Variety
Different and contrasting things in general. Combat? then show many different styles of attacks, use all signs not just the most normal ones like igni, aard and quen, dodge with different moves, show more environmental opportunities like the gas in the swamps, show physics and etc.
Exploration and world? show different weather types, storms, snowing, at night with no full moon, at dusk, many varied places like mountains, in small towns, in the sea, ominous caves and hideouts, the streets of Novigrad at night, show varied animals and how they interact between each other.
Characters and story? show varied characters, they dont need to be known ones or important ones, dwarves, trolls, elves, men, women, monsters, show the cinematic conversations between characters riding while talking, or walking in the city, different situations like quest talk, intrigue, heated discussions, threats.
Just dont let the game fall into a specific place, dont let it look like its an understandable and predictable thing, make it strange and irregular, impossible to say if its "this kind of RPG" or "this other kind", cause its The fucking Witcher 3, not out yet, and unprecedented.
2) Impressive scenes, shocking ones.
Show scenes that arent about letting you know what fans already know they will get, but rather that surprise us and force us to wonder what the game will really be like, and that they look amazing of course, with significant clear things happening that we can say "oh its the part where X happens". This can be anything from story events like in the witcher 2 trailers, or simple scenes of packs of horses running in the wild, a storm destroying your boat, flashy combat parts like Geralt using Aard from his horse to knowckdown an enemy rider, new gameplay mechanics that havent been presented yet, etc.
3) Strategical RPG elements
Show a lot of stuff regarding the strategical systems of the gameplay, short but sweet footage of combining plants to make potions and/or upgrading them, varied armor sets and how we change them replacing their separate parts with monster parts or something else, skill tree with some clear abilities shown and then cut to a scene in which Geralt uses them, crafting items and using some of those in combat like varied traps footage and bombs, show statistics and how we can change them a bit, customization of all kinds and some of its effects, Witcher senses and how they help uniquely in different situations.
4)Open world life
Show and talk about everything regarding the living open world, how people behave, why, how many animals are in the game and how's their AI, how do they interact with each other, try to resume in a video things like corpses attracting monsters of a specific kind to an area and now posing a threat to villagers, what happens when monsters get close to towns or a city, show what they all do in different weather conditions, and what do they mean for the player.
5)Type of footage
I personally don't think that its a good idea to show long raw uncut footage like the 37 minute demo, it gives trust and more direct understanding to viewers, but in exchange you guys reduce hype by turning the game into something more common, more mundane, like when we will play it. Whatever next gameplay you show, I suggest do it in medium to long trailers, 5 minutes minimum aprox., and get to a point, whether its presenting only one aspect, or showing new content in general for the first time. Avoid just demoing the game like any random lets player messing around in a quest, present your whole game in each of the videos, make the trailers something in the name of it, a video that I can send to a friend and tell him "here, this is TW3" without having to explain that not all quests are like those in the 37 min demo, or that combat can change, or that you're not always using the same armor, or that its not all swamps and the city.
I want fans to be pleased and continue to be engaged but also new players to be in awe with these suggestions.
