YouTube videos have the capabilities to support annotations. These are notes that are displayed in the video as it plays. They can be informational, narrative and even, interactive as they can link to over videos and YouTube urls.
Once you've got your video up on YouTube you can open it in the preview and start playing it. If you're not in preview mode you can click the Edit annotations button on the video's main page. When you get to the point of the video where you want an annotation click the Add annotation icon. There are three types of annotations available - Speech bubble, Note and Spotlight. Depending on the desired effect choose the one that suits your needs best. You can type the text right on the video or in the edit window on the left, as well as drag and drop the annotation wherever you like.
You will also see a list of all annotations on the left side of the page. Here you'll be able to edit the link, text and display times. Unfortunately, you can only link to other YouTube URLs. There's a very good step-by-step here. One of the other cool annotations is the one that can pause the video so that you can call attention to some particular area, frame or scene.
Why Use Annotations?
If you've got multiple videos that are in series you can link them together with URL annotations right in the videos. It is basically a way to network all of your videos together through an interactive feature in the videos themselves instead of just through the YouTube Channel and video organizer.
Annotations could be used for example to highlight specific parts of a video. Say you're a painter and you did some recent works for commission. You might have a virtual gallery describing the works, what they were for and other information. The annotations could not only inform but also link to other videos of your work. Perhaps you've done some construction work or want to video the process of building something. Well with annotations you can practically give step-by-step instructions without having to worry about dialog or reading cue cards.
The annotations can also be coupled with subtitles (which can be translated into multiple languages by YouTube) to complement them and add more depth of information. Between the two of them you might not need to worry about sound and dialog any longer as you can subtitle everything and explain it, even pausing the video to give the viewer time to consume the information.
Annotations might be one of the best innovations in online video since the creation of the interactive button overlay. In fact they're almost the same and not really new. But where Google and YouTube go, other follow
Annotations give you a way to offer far more information but still present it in a video format. Of course balancing the usage of the annotations so as not to overwhelm the video content or the viewer will be an art in and of itself. I suggest the PowerPoint rule of thumb I use - no more than three lines of text per slide, or in this case, per scene. The only major drawback I see at present to the YouTube annotation system is the fact that you can't link to a URL that is not part of YouTube. Of course I can also see why they have placed a limit on it.
With annotations at YouTube you can bet your bottom dollar that other sites will fall into line and begin offering something similar if they do not already.