«The children in the videos appeared to be younger than 13 years old, the minimum age for registering an account on YouTube. The videos themselves did not have sexual themes, but showed children emulating their favourite YouTube stars by, for instance, reviewing toys or showing their « outfit of the day.
The explicit comments on these videos were passed on to the company using its form to report child endangerment – the same form that is available to general users.
Over a period of several weeks, five of the comments were deleted, but no action was taken against the remaining 23 until Trending contacted the company and provided a full list ».

Source : Glitch in YouTube’s tool for tracking obscene comments – BBC News