Over the years, Grand Theft Auto fans have displayed a uniquely voracious appetite for rumors, leaks and news about the unannounced but finally confirmed 6th numbered mainline entry in the series. While attributed to Rockstar's radio silence on the matter, other parties have found ways to exploit this phenomenon to their own gain.
Usually, the go-to method for riding the hype wave involves posting leaks that may or may not be utter hogwash in order to gain 5 minutes of fame, or by mass-posting contrived or outright stolen text in GTA 6-related "articles". Now, users have reported a fresh, new way to try and scam gullible fans.
First noted by u/LegalWallhacks on r/GTA6, the ad would play before or during YouTube videos if the eldritch machinations of the algorithm deem you the sort of person into this stuff, based on your search history or the kinds of videos you tend to watch.
The ad itself is a frankensteinian abomination stitched together with footage from GTA 5, Need for Speed, The Crew, Forza and the Saints Row reboot. It is easy enough to recognize these other games if you dabble in the genre and stay up to date with new and upcoming titles, but GTA 5 and GTA Online have hit such mainstream numbers that many fans don't really play other games, or follow gaming media and news.

