I think instead of Youtube, pick apps that curate content on your behalf.

For example, try Kidzovo an app that curates learning content for kids, makes it interactive so kids are not only watching it passively. And we intersperse it with general questions like: "Why should you be nice to your neighbor?" and then parents can hear their kids' responses in the parents' section of the app.

Disclaimed: I work for Kidzovo.