This is propaganda. There is no way to ascertain from this footage if this is representative of Hamas' soldiers behavior, or what the total situation is.

That said, the most powerful propaganda is the truth, and showing kindness to even your worst enemies is a powerful weapon against them. Islam has strict rules about the treatment of captives and hostages and the behavior of the Hamas troops in this video is in accordance with my understanding of Islamic laws of war. Their behavior also seems to be in accordance with reports from Israel settlers who have stated that Hamas fighters took pains to re-assure them that they would not be harmed, and with the release of some Israeli women and children.

I am curious where the parents are. I would hope that they are detained safely, as it is concerning that the children are not with their parents.