Here are a few websites where you can watch clips and episodes of French cartoons.
Radio Canada – Vidéos (http://www.radio-canada.ca/jeunesse/videos/)
Here you can watch a great selection of kids French animation shows. These cartoons are those that you would find on Saturday mornings on the French channel through your cable provider. Near the top of the page, you can scroll through to see all the different shows that have episodes to watch. Léon is also available on this site. Don’t expect your child to be able to understand what the characters are saying. They might hear a key word or two that is familiar.
YouTube has a wealth of French videos, songs, and clips. I would suggest finding a particular channel to follow to ensure the content is appropriate for a younger audience. I would suggest channels like “comptines” and “comptinesmaternelle”.