An online system analyzes videos from video hosting systems to identify embedded contents in the videos. The online system associates embedded content with videos that include the embedded content. The online system determines statistics describing distribution of the embedded content by the video hosting system, for example, the rate at which the embedded content is included in videos and demographics of the users targeted for the embedded content. The online system may use the information describing distribution of the embedded content by other video hosting systems to modify the distribution of embedded content by the online system.