@Background Pony #FA24
 
@Background Pony #6D93
 
Precisely correct. The Raptorians were working for Porcina, an anthro pig known also known as the Glass Princess because she liked to turn everything into glass so she could continuously admire her own reflection wherever she went. But her magical cloak (which allowed her to turn things to glass) was worn and torn, so she ordered the Raptorians to cut off the little pony’s manes to weave into a new cloak.
 
Because all the little ponies are apparently innately magical (even the earth pones), their manes spontaneously regrew in about 3 seconds flat. They were then ordered to weave their manes to make Porcina’s new cloak, and she then repaid their service by (temporarily) turning Ponyland completely into glass! She turned good in the end though and set everything back to normal (as well as turning the evil Raptorians into glass if I recall)

They’re doing the Kubrick Stare.  

@Princess♠Molestia  
Rarity isn’t in G1. These creatures called Raptorians did the hair/manecuts.

@Background Pony #ACCD
 
It’s part of a four-part episode entitled “The Glass Princess”. This particular scene is in part 3 if I remember correctly.

what episode is it?

Going to assume a human villain is going to get thrown off a cliff. X3

I don’t think they. Like the mane cuts Rarity gave them.