IMHO, I think that spending more time working with the camera in different situations will get you farther than watching a video. Especially for the sort of situation you've described, I'm not sure a video would help more than "just doing it", then doing it some more.

If you're planning on doing paid work with the Hasselblad, you may want to shoot both with it, and your F5, until you gain more confidence. Use the Hasselblad for some of the set up shots where you have a little more time, and the 35 for candids and such.

Kids are a challenge, trying to keep up with my 3 YO nieces and get some good pictures on a play ground was quite an exercise, in every way!