The clip was of a live performance of Miley singing the hit breakup song and she ran to Selena's seat in the audience and the two sang their hearts out together.
The "Back To You" crooner took to the comments section and replied, "Tbt -such babies ?.”
Even Demi Lovato got in on the action and commented on the video by simply writing the word "iconic."
Earlier this week, in honor of International Women's Day, Miley also posted a series of throwback photographs of her Disney Channel days on her Instagram stories and wrote, "We define a f**king era! Sorry, not sorry." Demi shared some of the same pics and wrote back to Miley, "Hell yeah. Miss you @mileycyrus."
What are your thoughts on Miley's video and Selena's reaction? Sound off below!