I saw some of the video. Amazing and scary! Time to talk to the kiddos again – if the floor is bouncing like a trampoline, leave the building.
Something similar happened near Houston a few years ago. A family was having a Indian religious event. A large group of family members and friends were gather in a bonus room over their garage when the floor gave way. There were many serious injuries, since there were elderly relatives upstairs and I think some below.