I have written on multiple occasions about the educational potential of layering educator annotations and prompts on existing online content. My interest is prompted by the great amount of online content that could be improved as educational resources by such additions. There are a growing number of surfaces that provide this capability and they do so in different ways.
I will say upfront that there are some who object to this practice no matter the method used by a layering service. Some simply want their content to only be available as they have created it. While I can appreciate this position, I see a middle ground. As I suggested, the technology of how layering is implemented varies. Some techniques acquire the content from a source (a web site, a video available on the web), add the additions specified by second party, and then make the combined product available. Other techniques create a similar product by combining the product from the original developer and the designer wanting to add a layer of content each time the combined product is requested. What the user sees may appear very similar, but what is happening online is very different. In the second case, the server on which the original content creator has placed his or her content is involved each time someone uses the Internet to download the combined content to a browser. More to the point, activation of this server may be related to expectations that original author has for displaying ads or related sources of revenue.
So, take YouTube as an example. Some creators want their videos to include ads that appear when a video begins. They are compensated a few cents each time YouTube serves one of these videos. If I would download one of these videos and then serve it myself, the creator would not receive compensation when the video downloaded from my server was viewed. My use of YouTube content would not necessarily be inappropriate. My responsibility would not be to YouTube. I might make a request of the video creator, and if grant, serve the content myself.
In promoting layering services, I have made the decision to focus on services that involve the server used by the original content creator each time a viewer makes the request to view a composite product. This is the position I have taken in the book I have written on the subject and in the online content I have created to expand on the content in the book.
I great example of the type of service that meets the standard I describe above is TurboNote. This service allows comments/questions to be attached to video or web pages and then shared with designated learners.
I have created an example of an annotated video as it would be shared with a specific user. (TurboNote extension must be installed on Chrome browser to view)