He probably refers to the fact that the NRA initially tried to derail the case when initially brought, including its working to merely change the District's laws instead of having them overturned.
In short, the NRA blinked when the time came to roll the dice. The Heller's attorney didn't and the result is history.
That's being polite- the NRA tried to sabotage the case, Alan Gura punched them in the face in court basically, and after that point (and likely a few dump truck loads of hate mail sent to NRA HQ) they came to their senses and started to back Gura/Levy.
I think the NRA is generally useful but that was not one of their most shining moments in the recent past.
-Mike