ETFs partly responsible for "Flash Crash"?

[TraderInterview]

I was surprised to read this about ETFs being partly responsible for the flash crash day in May.

Seems a bit of a stretch but if anyone has insights please reply.

http://www.fa-mag.com/component/content/article/7-news/5556.html?Itemid=52

 

[hopeful]

If there is an inverse ETF for every regular ETF then their net impact would be nothing. Unless I'm wrong. Probably am.