Just like the R33 GTR video? The video was real, the car was far from factory specification (at the very least it is reported to have had a well conceiled rollcage, slicks AND increased boost).
So yes, you're right that there IS a video of a R35 doing a 7:29 lap of the 'ring, but there is no proof that the car was a stock factory spec car and not some tweaked test mule.