Having seen the episode, this was a deliciously misleading clip.

@Background Pony #8856
 
Mayor Marks is a placeholder name, just to answer your question.

Okay, if “Mayor Marks” (is that her name or are we just calling her that?) is our villain, then she better say “All ponies are equal…but some ponies are more equal than others.” at some point.

The True Villain of this arc could very well apply to my theory that The Spark is another entity. The unknown force that helped Twilight realize those five weirdos were her Pony Friends Forever, and what guided Cadance out of the caverns. Drawing a blank on what else it did, lol. However, it might be important later. Same goes for Rainbow’s and Pinkie’s extraordinary abilities. :3
 
(If I gave it more thought, one could persuaded to think Flutter, Rare, and Applejack also have their own extremely subtle special abilities. Empathic persuasion, McMuffin-seeking senses, and armour-piercing kicks respectively. I’d equate any six of the aforementioned to a hidden ability in Pokemon not normally listed or known without a FAQ or something. :j )

If they add this into the mix.  

@Hateot  
It’s possible that these scenes could be from two different episodes. If the Equalist or whatever it is is a season-arc villain, then we could be seeing conflicts in places other than the Equal Town of Idiotically Grinning Ponies.

@PonyPon  
It just felt a little odd that the scene somehow changed into a mountain range when they are all in a desert town. The Hearth’s Warming Eve episode was the first thing that came to mind.
 
Sure, they could be trying to make a “playground” of sorts for the ponies of Smileytown to make them remember/discover what they truly are, but those mountains still feel a little out of place. At least in regard to what little we know at the moment.

I don’t know why, but I get the feeling that Mayor Marks is going to turn to have been corrupted by an external force, and that that force will be this season’s arc villain. There’s something peculiar that the main antagonist be, at least visually, an otherwise innocuous and ordinary unicorn.

@Hateot  
Yes, it would be pretty crazy to think time travel would be involved with snow.
 
We do have weather controlling pegasai, remember?

Now that I think about it, would it be crazy to suggest all that snow means that instead of an elemental firefight, there’s going to be time travel of some sorts involved?
 
Seeing as the town looks to be standing in an arid locale.

Nice to see there may be a common looking pony villain that can pack a punch. Usually the really powerful ones have to carry a huge “I’m a monster sign” to be even considered a threat.

@Mojo  
She’s a Markist.

So I guess the villain this time around is just a unicorn with some really strange powers?

Looks like Twilight and co are escaping with ex-equal ponies in tow. If that’s the case…  

Inb4 Twilight and friends are owned, but the ponies they cured pull a friendship power and save the day.

Non-equality begone!

@Princess♠Molestia  
Rarity, too, if capable.

Uh Twilight. You can make force fields. Big ones.

WE ARE… HAPPY…

The rhythm of this is interesting.

They cured some. Neat. X3