That was extremely interesting, particularly the part about an index fund bubble possibly masking the usefulness of active management.
As an individual investor I don't think you should be worried. We are a long way from anything seriously disastrous happening because of index investing.
I feel that this is probably the case, but I'm 25 and my retirement is a long way off. It seems feasible to me that a major crash related to this could occur within the decades between now and then.