A large domestic cat was spotted on home surveillance video in the Georgetown neighborhood of Washington, D.C., on Sept. 15. It was not a mountain lion. (Video: Giulia di Marzo)

Update: Residents thought video might show a mountain lion in Georgetown. It’s a cat named Cookie, vet says.

At first blush, the surveillance video shows what looks like a very large cat. When a Georgetown resident noticed it Sunday on her home security camera, she worried it might be a mountain lion in her yard.

But wildlife experts said the video, which became popular on social media, depicts nothing more than a domestic cat.