Lots of YouTube videos carry annotations with links to related clips or other websites, but how many of them do you actually visit? Probably few of them, if any. However, YouTube may have a way to pique your interest. It's rolling out cards that both look much nicer -- compared to text boxes, anyway -- and are available at any time, not just at specific moments. They'll work on mobile, too, so you won't miss important contextual info just because you're on your phone. YouTube isn't ditching old-school annotations yet (it wants to fill out the cards' feature set first), but it's clear that their days are numbered.