Earbud removal is mandatory unless plugged into the IFE... it's somewhere in the CARs, but I'm not digging it up tonight.

It's one of the CARs which refer back to approved airline policies for an exemption to the blanket rule, same as the "no electronic devices during takeoff, landing and taxi" rule.

TC may or may not rule international flights which do not enter Canada but Air Canada policies do, and AC policies require TC approval.