I was over at Ardenwood Forge today and told Scott you posted a link to his video.
Interesting to understand the forge. It actually similates how an old celtic forge would have been, in the sense that they would dig a tapered trench in the ground, and use rocks as the sheilds. The oval sides similate the rocks, or how they would have forged.
There is some speculation on side blower vs. bottom blower.
If you look at the pics on my website, you'll see the one of the bottom. There's wire mesh that is wraped around the welded frame, and the mortar is spread over it. The forge is not heavy due to this, and can be picked up by one person.
Scott has another one also, I don't have any pics of it. Just turns out that the video had the one I did snap pics of.