Take the size of those laptop batteries in that video and multiply by 20-30 times and you can imagine what the video I spoke of looked like. Add to that the explosion was contained in a very solid and thick aluminum case with the exception of a small 1/2" vent, and it has all the ingredients to get interesting. The aluminum case was destroyed and the explosion was very impressive.
I did my battery powered LC+ Camelback with NiMh battery packs, it actually worked out really well.