Screencast 4.1
www.youtube.com/watch?v=PFuYWFWC7-w
This screencast walks you through how to construct the MO energy level diagram for O2.

Screencast 4.2
www.youtube.com/watch?v=qoYEOMMJCXc
This screencast walks you through the origins of s-p mixing.

Screencast 4.3
www.youtube.com/watch?v=estiedAlXII
This screencast walks you through how to construct the MO energy level diagram for HF.