Unreliable video evidence

Why did the defense not question the fact that the video tape 'evidence' of two black men entering the store was clearly of very poor quality.

Also that the video tape itself clearly demonstrated that the only witness had his back to the first man to enter the store had his back to this man during the whole time.

Yet the Prosecution claimed that the only state witness (Sam Vallabhbai) accurately identified Anthony Nealy as the murderer.

Why did the defense fail to point out that the video began with the only witness (Sam Vallabhbai) putting out boxes at the store and that he could not have seen the faces of the men that entered the store and committed the murders