The Problem of d.tube is, that it is really hard to delete a Video form IPFS. So the kind of videos you mentioned will stay there for a long time. Actually the information of these videos will stay in the blockchain forever. To delete them from IPFS you need to delete them from several nodes. You won't have control of all these nodes.
So, you are obviously right. There is a serious risk for kids on this Platform.
Unless their TOS has changed, dtube actually only hosts your video for free for a while and then will charge you to keep it online.