Here are screencasts of material for the lecture I was away for (Apr 19th, 2017). Also, since I might be a bit rushed when I talk about the divergence theorem (on May 1, 3) I made a screen cast showing parametrization invariance of surface integrals instead of doing it in class.
In addition to the video, you can download the PDF of what I wrote on the screen. Also, most of the material covered here can be found in my typed notes on line and surface integrals.
Conservative / potential forces. PDF of screen writing
Greens theorem and proof. PDF of screen writing
Parametrization invariance of surface integrals. PDF of screen writing