This person drives in a small car in other drivers' blind spots, waits for them to try to merge in front of them, then uses a novelty car horn.
Then they upload the video, which Reddit loves because it is watching someone else possibly make an error thereby making the viewer feel better about themselves, and then they get an opportunity to share a link for the horn in the comments when people (or maybe the original poster’s alternative accounts) inevitably ask where they can also get a horn like it:
I do not see what other explanation there could be for why a person is recording and uploading so many incidents of the same type within such a short timespan.
That sort of incident happens every day in the Bay Area, but people just yield or pre-emptively make room when they see the other guy is going to do this. This guy has decided not to and so he's got a lot of videos. That's literally it. If you decided to hardball every driver interaction you'd have enough of this content too.
Then they upload the video, which Reddit loves because it is watching someone else possibly make an error thereby making the viewer feel better about themselves, and then they get an opportunity to share a link for the horn in the comments when people (or maybe the original poster’s alternative accounts) inevitably ask where they can also get a horn like it:
https://www.reddit.com/user/Muscles_Metal_Miata/
I do not see what other explanation there could be for why a person is recording and uploading so many incidents of the same type within such a short timespan.