From camping with pop-up canopies you find out the you need two guy wires per corner or it will collapse or fly off the same way in the wind. Another way is to put guy wires in Xs on 5 sides of the cube and nail that puppy down. Use both techniques and that canopy will not budge much. The fact that these guy wires where not put on should be looked into.
I didn't see any rigid cross bracing or guy cables that should have prevented sway or buckling of the support columns. Once the back edge dropped the next row of supports tilted forward and everything else then went forward and down to the stage platform.
That is a good idea. Maybe they could have flags at the top of the structure that are weighted so that they only unfurl at winds above a certain speed, or a small sensor that sounds an alarm. I suppose those aren't complete solutions, but just a start.