Q. May I use rented videos in my class?

So long as your screening of the video will fit the criteria detailed under section 110(1) of copyright law. 

Notwithstanding the provisions of section 106, the following are not infringements of copyright:

(1) performance or display of a work by instructors or pupils in the course of face-to-face teaching activities of a nonprofit educational institution, in a classroom or similar place devoted to instruction, unless, in the case of a motion picture or other audiovisual work, the performance, or the display of individual images, is given by means of a copy that was not lawfully made under this title, and that the person responsible for the performance knew or had reason to believe was not lawfully made;