Fix stereo channels in video lectures

We just noticed that these videos from Luc's UChicago fall class were recorded in mono instead of stereo (or one channel, often the left one, is much clearer and louder compared to the other). You can test this with headphones.

Please download these 7 videos:
https://www.youtube.com/playlist?list=PLzREt6r1Nenkr2vtYgbP4hs44HO_s_qEO

and duplicate the louder/clearer channel (e.g. from left to right) so we get the full stereo effect. E.g. [here's a way to do this](https://www.youtube.com/watch?v=WjWHyJ88bPs) in Adobe Premiere Pro but VLC etc. has similar functionality.

Once the audio is equally clear on both channels, please re-upload to the site. I'll send you the log-in info for our YouTube siteseparately.

The UChicago AV team will be taping Luc's spring lecture as well on Mondays and Wednesdays, so we'll need to update two videos per week to the site.