You cannot annotate videos directly in Annotation Studio, but you can upload and view videos in Annotation Studio, while annotating the text around the video.
To upload a video into Annotation Studio, simple copy and paste the embed code into the text on the Document Upload Page. For example, in the screen shot below, I have pasted the embed code from a clip on YouTube into the text.
Note how the code has been pasted into the text view, not the code view. Video code will load properly from either view.
The video will appear and play now within the text, as the following screen shot.
Please note, video code pasted into a MS Word document will not display properly in Annotation Studio.