I love this channel as well as Primitive Technology, but this video is particularly interesting in light of typical game tech trees in Minecraft, UO, etc. This guy claims the stone axe is 30-50% as effective as steel, and I think the evidence bears that out!
If you are REALLY interested in comparing materials, I enclose a link to a paper written by James R. Mathieu and Daniel A. Meyer (Boston University) regarding 'Comparing Axe Heads of Stone, Bronze, and Steel: Studies in Experimental Archaeology'
For me, the easiest way to understand and interpret are the graphs.
I never thought that comparing materials could be so interesting and that does not even compare stone with flint etc.
Okay, that paper is seriously awesome.