Following on from a similar update earlier this year which allows members of groups on the social networking site to watch clips in sync while commentating and reacting together, it could be rolled out to the instant messaging service.
According to some new codded added to the app - spotted by developer Ananay Arora - it looks like the feature could be coming to Messenger.
It appears it would allow users to drop a clip into the chat, and then ping the other users - or group of people - in the thread so everyone can watch the video at the same time.
Although Facebook has told TechCrunch that the code is just an "internal test", it could be something users see in the future - even if a timeline isn't clear at the moment.
The new reports follow plans unveiled earlier this month that show that Facebook Messenger is looking to introduce a feature to delete sent messages.
In the release notes for Messenger's 191.0 version on iOS, it says: "Remove a message from a chat thread after it's been sent.
"If you accidentally send the wrong photo, incorrect information or message the wrong thread, you can easily correct it by removing the message within ten minutes of sending it."
The feature is listed as "coming soon", and there has been no specific date set for a roll out to users.