How to make clouds using particles and smoke simulation (Cycles) I've watched this over 20 times and I'm just not getting it.

https://www.youtube.com/watch?v=gEJRrRLRHJA

There's not a lot of 'why' to this tute, so I can't adjust for different situations. I think a lot of my probs stem from scale. Settings for one size of model and smoke domain just flat out don't work for another scale of cloud model.

Can anyone recommend a better vid on this method? One that points out what to change and why for different sizes?

Also, bear in mind this is not for a static image: it's for an animated model of a world where the clouds move around a planet, so the general idea is to set up a sphere with a thickness that will sit around the planet sphere, and rotate.
Your question and description is not clear. 
So just a notes:


Doesn't matter how big a smoke domain object is, domain is defined by resolution in physics properties. Imagine that as a grid. Resolution means into many voxel pixels will be divide the longest edge of the domain.
Higher resolution = more details for this voxel texture. I hope you already checked Blender Reference Manual.
Second aspect is already explained in your link - play with size of procedural texture used for particles density to create general shape of clouds. And adjust brightness and contrast to tune the particle cloud shape. (I use rather coloramp for that.)


Don't expect precise numbers - nobody knows your planet size or what style of clouds you want to achieve.