Music videos made for kids on youtube are free, but are they really considering the amount of work an artist has to go through to make the video. Additionally many videos are monetized by google by using advertisements. Somebody is paying for them somehow.
Reactory Factory TV provides music videos for kids and does not monetize it. Google and the artist are still receiving some add revenue however. The difference is that the videos are presented in a safe environment that is easy to watch for kids.