I haven’t found any other than http://www.detonationfilms.com. They have a large amount of FREE fire, explosion, smoke and other, well, detonation footage. The quality is pretty good, but the price is fantastic! Hope this helps a bit, and I would like to find some free stock footage as well, so if I find any, I’ll be sure to relay the info!
Funny how creatives think outside of the box. And yet the majority of their work is presented within one. Perhaps that is why they collect from the outside, to show what’s inside. -James Neil Teague-