First, in regard to the video you posted, I think that Carrier, while looking woefully unprepared for debate, makes a number of excellent points, which aren't addressed by Craig. Craig's argument hinges on the belief that the Gospels are individual accounts of Jesus, when in actuality, it's likely that the writers were well aware of this story through a common source. Craig makes a huge assumption when he states that this source is first hand knowledge. Also, I find it odd that Craig so easily dismisses Carrier's evidence of literary devices in scripture. In fact, the apocryphal Epistle of Barnabus, which is believed to have been written ~70-130 specifically mentions the comparison of Jesus to that of the temple scape goat. This, at least, shows that early Christians were certainly aware of this idea.
Which leads me to the core question of their debate: how do we know which stories to believe? Should we accept all other oral traditions and ancient writings as mostly true? Even within Jewish oral tradition there exist stories which are obvious works of fiction.
To me, all credibility is lost if historical inaccuracies exist in a text that is used as evidence to support a historical event. The fact that fabrications and forgeries are quite common in early Christian writings also causes alarm and raises questions about the 'sacred nature' of traditions in the early church.