On youtube at least, competitors can flag videos as ‘ungood’ in a number of ways (copyright, hate speech, NSFW, etc.) to entangle their competitors in bureaucracy.
Not just YouTube. One of my competitors spent thousands of dollars on AdWords to send traffic to my site with an ad for something completely unrelated.
This of course led to bounce rates of 99%+ for all of this traffic, which dramatically increased my bounce rate overall.
As far as I can tell, Google used this as a signal that my site was a shady/scam site and removed me from the search pages I used to rank on entirely.
Took nearly 6 months to figure out the problem, and where all this phantom AdWords traffic was coming from.
