They bought Vine. Story still holds though.

Okay, a citation: I didn’t realize this either, but there are many articles about it from 2012, such as: https://www.linkedin.com/pulse/why-twitter-bought-vine-befor...

“Why Twitter Bought Vine Before Launch”

Or https://thenextweb.com/news/twitter-acqui-hires-pre-launch-v...

“Twitter acquires pre-launch video sharing startup Vine”