Youtube has added a new feature called Annotations! This is awesome for video producers because it allows you to write notes on your video! Include popup text with links and you can have some major kick ass videos! Imagine you say a URL – now you can write it out in the video and provide a link to it for viewers to click on during the video!
This is fantastic thanks Youtube!
[Correction]
Currently links can only be to: YouTube Video, Channel, or Search result.
Also currently the text is only available on videos embedded on Youtube.
My How-To Annotate video: