For those that are interested, you can watch Mexico's game tonight online for free (although it does require a sign-up). Might as well get a preview to see what Canada is up against!
http://www.concacaftv.premiumtv.co.uk/
It is an official video provider to Concacaf. It doesn't appear that either of the Group B games will be on Sportsnet tonight, so this will be your only way to see them.