What do you prefer? When screencasts are clearly narrated while they are being recorded, such as Merlin Mann’s desktop tour or when it is obvious (or at least appears obvious to me) that the voiceover was added after the video portion was recorded, such as this screencast about Blogo? (I should mention that the Blogo screencast isn’t the best example of when voiceovers go bad)
I’m more of a fan of the first variety, since it makes it much easier to follow along with what the presenter is doing. On the other hand, the second method allows the narration to be much more polished. In my mind it comes down to a decision between more natural vs. more polished (but not necessarily more professional).
What do you think?