Can you post the link to the video? Without seeing it, no one can really judge if the action was dangerous or not.I'm sorry , I should've been more clear! The 2 year old wasn't on a tank. Just freedive. The dad took him down like 8 or 10 feet and took him up. U guys think there's any risk to that?
In the case of my children, I did never "push" or "pull" them down.
They learned to retrieve toys from the bottom of the pool by themself.
I just tried to show them the proper ways of using fins, or the manouvre for going down raising the legs above water ("capovolta" in Italian, I do not know the English name).
Children mostly learn by imitation: no need to force them down...
Regarding the risk, of course barothrauma is the only relevant one.
Both my children did learn to equalize properly before being 2 years old, so if the child equalizes properly, there should be no risk freediving to 3 or 4 meters...
But, as said, at 2 years old, with proper mask and fins, a child should be able to do it autonomously.