French Kids Movie
I searched on youtube for kids movies in French and all I saw was 'Matt le magnifique'. I saw it in school.
I'm not quite sure what you're looking for since Matt le magnifique is not a kid movie, but I would recommend Peppa Pig https://www.youtube.com/channel/UCXptamDYEVcU4JCio30hYTw
LEO & POPI (this one is a bit old) https://www.youtube.com/watch?v=csIQbjACHcA
There are more of these types of shows at https://www.youtube.com/channel/UCBlQZu0qEvaUH6jzNvZAm3w
The best way you can learn French, from movies is watching movies that you already watched in English. For some example, I recommend Ratatouille, as it is in both English & French. It's also for kids. Bonne Chance! ;)