13. A non-transitory computer-readable storage medium storing instructions which, when executed by one or more processors, cause the processors to perform operations comprising: presenting, on a web page, a text entry field for a text string to be entered by a user; receiving the text string, the text string including a delimited label list; parsing the delimited label list to determine a number of, and labels for, categorized user-selectable interface elements to display; presenting a graphical interface that includes a motion video presentation and the number of categorized user-selectable interface elements, each user-selectable interface element having a separate label from the delimited label list; receiving, through the graphical interface, at a first moment during the presentation, a first selection of a first interface element of the categorized interface elements; in response to receiving the first selection, storing first data that maps a first category, corresponding to the first interface element, to a first time point at which the motion video presentation was being presented at the first moment; and generating, based at least in part on the first data, a first tracking graphical element that indicates at least a first quantity of times that the first interface element has been selected during a first time interval that includes the first time point.
13. A non-transitory computer-readable storage medium storing instructions which, when executed by one or more processors, cause the processors to perform operations comprising: presenting, on a web page, a text entry field for a text string to be entered by a user; receiving the text string, the text string including a delimited label list; parsing the delimited label list to determine a number of, and labels for, categorized user-selectable interface elements to display; presenting a graphical interface that includes a motion video presentation and the number of categorized user-selectable interface elements, each user-selectable interface element having a separate label from the delimited label list; receiving, through the graphical interface, at a first moment during the presentation, a first selection of a first interface element of the categorized interface elements; in response to receiving the first selection, storing first data that maps a first category, corresponding to the first interface element, to a first time point at which the motion video presentation was being presented at the first moment; and generating, based at least in part on the first data, a first tracking graphical element that indicates at least a first quantity of times that the first interface element has been selected during a first time interval that includes the first time point. 14. The non-transitory computer-readable storage medium of claim 13 , wherein the operations further comprise: receiving, through the graphical interface, at a second moment during the presentation, a second selection of a second interface element of the plurality of interface elements; in response to receiving the second selection, storing second data that maps a second category, corresponding to the second interface element but not the first interface element, to a second time point at which the motion video was being presented at the second moment; and generating, based at least in part on the first data and the second data, a second tracking graphical element that indicates at least (a) the first quantity of times that the first interface element has been selected during the first time interval that includes the first time point and (b) a second quantity of times that the second interface element has been selected during a second time interval that includes the second time point but not the first time point; wherein the first interface element is a first color; wherein the second interface element is a second color that differs from the first color: wherein the second tracking graphical element includes a first quantity indicator that is the first color and that indicates the first quantity; wherein the second tracking graphical element includes a second quantity indicator that is the second color and that indicates the second quantity; wherein the second tracking graphical element is a bar chart; wherein the first quantity indicator is a bar, in the bar chart, having a size that is based on the first quantity; wherein the second quantity indicator is a bar, in the bar chart, having a size that is based on the second quantity; wherein the first interface element is a first button having a first label; and wherein the second interface element is a second button having a second label that differs from the first label.