Dave,
both my K5's - the one returned to shop cause of stains suspected and the new one - do the same thing occasionally. And know what? I don't really care, sorry
(I don't shot video, at least today)
As a workaround I see two ways to go:
- try using some external plug-in microphone. I'm not sure whether it works or not, gonna give it 70\30
- try using external sound recording device (lots of these pocket babies are widely available at almost every shop). You'll only need to synchronize the tracks and the best way here is to snap your fingers either at the beginning or at the end of video track. All the video editing/authoring software that I'm aware of supports adding/mixing external audio tracks
Good luck,
Zig