Really...???? there are many proofs if you are willing to research them, which will show us that not only HFT caused the flash crash but more that it was one specific firm's algo that cause it all,yes you hear it right. just at the beginning the narrator speaks Deutsch and some others minor interventions the rest is in english so you should be fine http://www.youtube.com/watch?v=x8SMjyXdc3I
LOL at the journalists waiting in front of the companies headquarters. "You see, it's inside this complex that evil happens. They will soon ask us what we are doing waiting in front of their property for 30 mins for no reason" Incredible, huh? So bad that the bosses don't look like Blaufelt, Goldfinger or the Emperor of Star Wars.
See ogarbitrage's post (5th poster in the thread) for some papers on effects of HFT ... http://www.elitetrader.com/vb/showthread.php?s=&threadid=217603&highlight=HFT