A programmer on GTAForums called "teamaker" confirmed that the video was verified by a representative of Rockstar logging into Leeway's account.
These breaks are so serious and legitimately made, genuine or fake, that they have gotten more public than the very cool GTAForums section at first.
Various clips from the break show both male and female protagonists, matching various reports about what's in store for the game in the near future.
GTA 6 has been running since 2014, so it is reasonable to assume that improvements in the long run will be varied.
According to Tech Crunch, Rockstar recently moved the credits from GTA 5 and GTA 5 Online to their own page and changed it to a "Thank you" page, indicating that they are slowing down the dynamic improvements of the title.