[plt-scheme] DrScheme tour screencast (sound volume too low)

Thank you all for the feedback.

For a very long time nobody said anything about the audio; suddenly I
have started to get these remarks in a string.  (I also didn't notice
these audio problems myself, initially.)  Given that, I wonder whether
something happened at YouTube -- they re-sampled something, or re-did
the conversion or Flash embedding, and that caused the problem.
Otherwise, it seems odd to me that there would be such a stark
temporal shift.

Anyone here w/ expertise on making such recordings?