How to create dynamic clouds? Specifically dense clouds that move really slowly, just fast enough to be noticeable in a 15 sec animation. They'll need to be 3d, interact with some floating buildings and reflect the sky. I found the dragoneex plugin "dynamic sky" to be great but the clouds don't move. Should I just modify it? If so, how do I go about doing it?
First of all go here and read this answer: How to use Blender's dynamic sky add-on?

Go to Node Editor and switch to World mode.

In paragraph Night sky with stars (from the linked answer) you can see whole node setup for Dynamic Sky add-on. Find part Clouds/Stars and Texture Mapping node there:



Now you can animate any of the Location values to get clouds moving in chosen direction.