1. A method for annotating a video, comprising: displaying by a computer on a device a video player graphical user interface, the user interface including a display area for presenting a video and associated control buttons; displaying, by the computer in the display area, a frame of a video; receiving, by the computer, a user selection of a region of the displayed frame; responsive to the selection of the region, displaying, by the computer, an annotation definition indicating the selected region; receiving, by the computer, a user selection of a control button to create an annotation; providing, by the computer, a display area for receiving user input of annotation content; receiving, by the computer in the display area, user input of annotation content; displaying, by the computer, a timeline associated with the video; and indicating on the timeline a marker associated with the annotated video frame.