This moment just utterly ruins the entire episode. It's bad enough that - somehow - wings have become articulate enough to use as digits, but this scene just wantonly disregards the laws of conservation of energy. Just moments before we see that Zephyr's wings are the same size as those of Rainbow Dash, but somehow they expand to at least three times the size! Even if we consider the possibility that ponies are actually balloons, there is no way that the feathers would be able to bend without outside - not inside - pressure.
Ugh. -5/10, could not watch again.