Hey Theo, pretty interesting. I went looking for a price on that stuff, you have to write the company in the UK for it. Seems it might be real expensive if they hide their prices!
I even looked for it on EBAY and EBAY UK but no luck.
I think I saw something similar in The Whole Earth Catalog many years ago. That was an extensive list of hippie-ish, back to the garden products and ideas; similar to The Mother Earth News. I still have it from around 1970 I think.
They had a similar technique to build a shelter with concrete and burlap bags! You have to make a framework with chicken wire, then get the burlap bags coated in wet cement and drape them on until you have it covered.
The British guy that narrated the video in your link reminded me of Terry Thomas http://youtu.be/DP7Ulkq4i7E