Youtube annotations allow video creators to add clickable links to certain parts of their videos. This was originally designed to create simple transitions from one video to another, but as with all technologies the best results have come from putting it to previously unimagined uses.

Here are four of the best examples of how it’s done, and one cautionary tale.

Where’s dexter?

To promote the new season of the TV Show Dexter, the US network Showtime created a mini-game called ‘Where’s Dexter’ – a video version of ‘Where’s Wally’. The game has several levels, with the prize being a viewing of the trailer for the season.

Truth or Fail

Hank Greene (of vlogbrothers) used Youtube annotations to create an interactive video quiz show called Truth or Fail.

Youtube Fighter

Interactive Parkour

Kak√°

And just to balance things out, here’s a video I consider to be a bad use of video annotations. Links that let you control the camera angles of the video. There’s nothing wrong with it in principle, it just seems as if they made use of the technology simply because they could, not because it would lead to great content.