Everyone knew it was coming the second Obama uttered the words "the private sector is doing fine" in the midst of trying to make a different point but the speed which the RNC turned this around isn't the focal point, the video's content is.
In 2008, John McCain said "the fundamentals of our economy are strong," and team Obama immediately used that small sound bite and produced an ad asking "How can John McCain fix our economy if he doesn't understand it's broken?"
Fast forward to 2012 and Barack Obama says "The private sector is doing fine," and the RNC immediately pounced, despite Obama attempting to walk back that comment in followup statements, and created an ad asking ""How can Barack Obama fix our economy if he doesn't understand it's broken?"
The two ads are shown below. Under those is the Mitt Romney ad in response to the Obama gaffe.
2012- RNC "Doing Fine"
2008- Obama "Fundamentals"
[Update] Mitt Romney also got into the actions after Obama's ill-chosen words:
Ad title "Fine?"