1. A content annotation method, comprising: receiving, from a first device associated with a first user viewing multimedia content, a first annotation including an image and an indication of a first annotation duration wherein annotations of the first user include source identification features indicative of the first user as a source of the annotations; wherein the source identification feature comprises a source identification avatar; associating the first annotation with a first temporal location of the multimedia content; providing, by a data processing system, the multimedia content, the first annotation, and the first temporal location to a second device associated with a second user of the multimedia content, wherein, upon displaying the multimedia content, the second device displays the first annotation at the first temporal location, for the first annotation duration, overlaying the multimedia content; and responsive to receiving a second annotation, a second temporal location, and a second annotation duration from the second user, the first device, upon displaying the multimedia content, displays the second annotation at the second temporal location, for the second annotation duration, overlaying the multimedia content.