(This series is not very long, and I would highly, highly recommend watching all these videos with your children and discussing them. This one made for children.)

You Are Loved
These You Are Loved videos are just a small portion of the curriculum created by the trusted theologians and award-winning film studio at the Augustine Institute. Signs of Grace is the only comprehensive sacramental preparation program for children that includes a thorough family faith formation component.
https://watch.formed.org/you-are-loved-1

For Children: The Miracle at Every Mass
Every Sunday, we get to witness a miracle. Sometimes it can be difficult to wrap our minds and hearts around this fact. In this Bonus Episode of Presence: Mystery of the Eucharist, Fr. Riley will give us a special, close-up look at the Eucharistic miracle at every Mass.
https://watch.formed.org/presence/season:1/videos/para-ninos-the-miracle-at-every-mass

If you think this is age-appropriate (not aimed too young)
YouTube - HOLY KIDS: The Eucharist (series)
https://youtube.com/playlist?list=PLSzL3M7UrnS-2Fj0kn4pBmaM5JV2haSCz&si=pFtQgk9mlvFArw6c

For Parents: Preparing Your Child for First Holy Communion
The Catechism of the Catholic Church states: "The role of parents in education is of such importance that it is almost impossible to provide an adequate substitute" (CCC 2221). Although the parish helps to form our children in the faith, no one can take the place of the parents' role in forming holy individuals. In this Bonus Episode of Presence: Mystery of the Eucharist, catechetical experts and practiced parents give practical advice for preparing children for their first Holy Communion. Parents will be inspired to make the Eucharist the source and summit of their family life.
https://watch.formed.org/presence/season:1/videos/for-parents-preparing-your-child-for-first-holy-communion

The Story of the Eucharist
God is the Master Storyteller. He authors His great love story not only with words, but with deeds. All of God's mighty deeds throughout history make up one beautiful narrative of salvation, which culminates in the Paschal Mystery. Jesus's teachings and actions throughout his ministry prepare for the moment he offers himself for, and to, each of us, fulfilling his promise that "My flesh is food indeed, and my blood is drink indeed" (John 6:55).
https://watch.formed.org/videos/the-story-of-the-eucharist