Meanwhile, they’ve added two new videos in their"Waves Smart Contracts" playlist on YouTube:

This one will tell you how to create MultiSig account right in their Waves Client — https://www.youtube.com/watch?v=OIQoheOYJw8

And this one is about MultiSig account creation via Waves IDE tools — https://www.youtube.com/watch?v=8DKRGnwsBjk