  Online video services, messaging systems, games and social media services are
tremendously popular among young people and children in many countries. Most of
the digital services offered on the internet are advertising funded, which
makes advertising ubiquitous in children's everyday life. To understand the
impact of advertising-based digital services on children, we study the
collective behavior of users of YouTube for kids channels and present the
demographics of a large number of users. We collected data from 12,848 videos
from 17 channels in US and UK and 24 channels in Brazil. The channels in
English have been viewed more than 37 billion times. We also collected more
than 14 million comments made by users. Based on a combination of text-analysis
and face recognition tools, we show the presence of racial and gender biases in
our large sample of users. We also identify children actively using YouTube,
although the minimum age for using the service is 13 years in most countries.
We provide comparisons of user behavior among the three countries, which
represent large user populations in the global North and the global South.
