As a non-flyer I will not comment on the approach itself.
With reference to what Rainboe is saying about the change in background volume with the alerts being sounded, some digital camera microphones seem only to pick up the clearest sound. So when the voice alert is occuring which I assume is quite loud, the microphone will pick this up clearly at the 'expense' of reducing the slipstream noise.
As the voice alerts stop, the microphone becomes more sensitive to the ambient noise levels and the clarity of the slipstream noise becomes more apparent. (Jet A Knight I didn't see your post before but this is what I mean)
In Rainboe's defence however, I have found a clip, again on youtube, that is a perfectly normal approach with some added sound effects to mislead the audience... so it does happen...
YouTube - Landing with upset airplane