A Reddit user, Bullgrit,
The highlight intro is clipped from a cinematic released ahead of the launch of the event where Moira, as a member of the Blackwatch, kills a Talon soldier.
The highlight intro would be a break from the norm as previous highlight intros usually have not involved other characters besides that of the player whose highlight is playing.
Moira's involvement in Blackwatch and her true intentions
You can get the Moira skin for yourself in the new Overwatch Archives Event which is available now on all platforms.
Photo Courtesy of Blizzard