If you've never done any dancing, you might find it hard to learn and teach it from a video.

I'd suggest you contact ballroom dance studios near you. I think you might be able to find a volunteer to help you--maybe a trainee instructor or an amateur who's been dancing a while. Even if the studios couldn't help directly, I bet they'd be happy to let you post a flyer asking for a volunteer.

If you have the time and a little money, you might want to take a few lessons (most studios have cheap introductory packages) or a group class yourself so you can "stay ahead" of your class.

I'd recommend that you pick one or at most two dances to work on. East coast swing would be fun for the kids, and they could do it with a two-hand hold, which might be easier at their age than closed dance position. If you want to do a more "traditional" dance, waltz would probably be good, as it has a steady beat and just requires counting up to 3!

I think it's great you want to introduce your kids to ballroom! And you might even get hooked on dancing yourself!