10. A system for providing content segments to a first resource having a first video, comprising: a processor; and a computer-readable storage medium having encoded thereon a program of instructions executed by the processor, wherein the processor: systematically browses one or more second resources hosting a plurality of online documents, the one or more second resources unaffiliated with the first resource; identifies the first video embedded in an online document of the plurality of online documents; extracts contextual information from the online document; generates a set of criteria based on the extracted contextual information; receives a request for a content segment from the first resource; selects a responsive content segment based on the set of criteria; and provides to the first resource the responsive content segment to be displayed with the first video.
10. A system for providing content segments to a first resource having a first video, comprising: a processor; and a computer-readable storage medium having encoded thereon a program of instructions executed by the processor, wherein the processor: systematically browses one or more second resources hosting a plurality of online documents, the one or more second resources unaffiliated with the first resource; identifies the first video embedded in an online document of the plurality of online documents; extracts contextual information from the online document; generates a set of criteria based on the extracted contextual information; receives a request for a content segment from the first resource; selects a responsive content segment based on the set of criteria; and provides to the first resource the responsive content segment to be displayed with the first video. 17. The system of claim 10 , wherein the responsive content segment is an advertisement.