That's a good video. At the beginning at 0:28 he talks about beaming and torsioning testing and that most SFCs are just good for "ballast in the boot after you cut them up". If aslanefe, our resident aeronautical engineer will chime in here (I'm an electrical engineer and didn't deal much with structures) he could tell you how thick a single plate of steel would need to be to equal the strength of a rectangular steel tube. I'd rather not revisit my college days in my retirement to look that up. If you notice, starting at 3:35 they welded in a hat shaped beam, turning it into a rectangular steel tube. Good stuff, and it is further verification of the torsion test shown much earlier in this string. SFCs without bracing from side to side do next to nothing for torsion.