8. The method of claim 7 wherein the monitored user interactions comprise a direct user interaction between the first video and the second video and an indirect user interaction between the first video and the second video, and wherein the direct user interaction contributes more to the co-interaction score than the indirect user interaction.
7. The method of claim 6 wherein a co-interaction score between a first video of the primary video subset and a second video of the secondary video subset is proportional to a number of monitored user interactions with both the first video and the second video.