Why does anyone care if "twice as many students skip lectures" when the videos are available online? If they're literally just providing transmission of information, then surely video is a bettet, more accessible format?
Also, I'm pretty sure the situation is more complex, as this paper from LSE demonstrates:
http://eprints.lse.ac.uk/50929/1/Karnad_Student_use_recorded_2013_author.pdf (PDF)