@ Kardi
The original is 720p (1280x720) and is downloadable on the site. On the right hand side about two thirds of the way down the page is a box named "About this Video". below this is a link "Download this Video". If you right click on this and choose "save link as" you can download the original 40mb video file.
@Franco-Jo
Err yes it probably would !
And, "20 minutes" !! Holy SFX Batman!
However what took the time in this shot was the volumetric rays. They needed high quality and render settings to avoid noise. Without that the frames were rendering at about a third of the time and still "boiling". If its locked off you may be able to get away with putting in any rays in post.
@ TU and Broc (sorry

)
The boiling cloud setup is very simple, three nodes total. All I did was add in a transform node between the Density and Cloud node. This was then animated in the X and Z direction to move the clouds to and from where I wanted them and the +Y direction to get them to "Boil". (next time I will try -Y). Technically I don't see how you can get "proper" cloud boiling in terragen. In proper boiling clouds small cells grow, expand and overlap to become larger cells (something like this Terragen could do) but they are also constantly replaced by smaller cells (which also grow, expand etc) and this second part I can't see how to do in Terragen. You cant constantly re-seed a low scale PF and have it growing to a large scale PF
AND have it constantly replaced by lower scale PF, or can you?
@TU and Oshyan
I'll be using Nuke to blend the layers and AE to make the final. I'm having some success working out all the blending nodes already. The posted version has a very small amount of de-noise applied. And thanks for the FB and G+ posts

Cheers
Richard