Tesla isn't your average automaker. The company likes doing things in untraditional ways and enjoys disrupting the industry. This also seems to be the case with how they recruit employees. The video isn't just about Teslas farting, you watch employees review some of the new updates that came out in the "holiday" software release this past December.
The video starts by showing two different ways to program the horn. The "posh" way sounds a voice with an English dialect saying "Well, I never," and then there is the fart horn, which actually makes a farting sound outside of the car. Personally, I'd rather have someone fart at me than honk at me.
The new "boombox" update allows owners to play different sounds through the car's external speakers. The new external speakers were added in late 2019 so that Teslas can emit warning sounds for pedestrians who might not hear the car coming. This is now required as part of the "quiet car" federal regulation in the US.
However, the external speakers don't just fart and make snarky comments. As you can see in the video, Tesla employees have the car play Jazz music that can be heard outside of the car. Tesla allows owners to add customised sounds too. Keep in mind, you can still play fart noises inside the car as well.
Towards the end of the video, you see one of the employees playing Battle of Polytopia, one of the new arcade games you can play in the car. The other two new games are Cat Quest and Solitaire (Kabal).
So if you hear a Tesla driving by with V-12 engine sounds, don't be surprised, because it's already been done.