14. The system of claim 9 , wherein the processor-executable executable instructions, when executed, further cause the at least one processor to: receive content revenue responsive to providing content item for display in the content slot; and share the content revenue with a video publisher that publishes the video document.
9. A system, comprising: a primary video content server including at least one processor and at least one storage device storing processor-executable instructions which, when executed by the at least one processor, causes the processor to: receive a video document, the video document including video content to be provided for presentation and embedded with an encoding specifying one or more content slot locations; determine based on the encoding embedded in the video content, the one or more content slot locations at which to insert content slots, each of the content slots configured to receive content items for presentation, each of the content slot locations having a start time that corresponds to a time of the video document at which to insert the content slot; insert the content slots at the determined content slot locations of the video document, the content slots configured to receive content items; receive, from a client device, a request to provide the video document for presentation; deliver, to the client device, responsive to the receipt of the request to provide the video document, the video document for presentation on the client device, receipt of the video document causing the client device to: (a) initiate playing the video document using a content rendering application, (b) execute, subsequent to initiating playing of the video document, the encoding embedded in the video document specifying the one or more content slot locations, (c) generate, based on executing the encoding embedded in the video document, a request for supplemental video content to insert at the start time corresponding to the time of the video document at which to insert the content slot, and (d) transmit, to a secondary video content server including one or more processors and memory, the request for supplemental video content to insert in the content slot, receipt of the request for supplemental video content causing the secondary video content server to: (i) select a content item from the plurality of content items to serve in the content slot of the video document based on the request for supplemental video content and; (ii) provide, to the client device, responsive to the selection of the video content item, the video content item for presentation on the client device at the time of the video document at which the content slot is inserted; and (e) insert, responsive to receiving the video content item from the secondary video content server, for playing at the client device, the video content item into the content slot specified by the encoding embedded in the video content document.