I'm working on a series of CSS/design screencast tutorials that sounds like it suits your needs exactly. The series is aimed at developers. The series will guide the viewer through designing the most common pages like landing pages, contact forms etc. focusing more on design choices and principles rather than on CSS technicalities.

I wasn't planning on using bootstrap though because I think bootstrap offers too many possibilities to developers who don't understand design. I think keeping things simple and limited is the best approach.

Do you think not using bootstrap would be an issue?