11. A system comprising: a database configured to store: a plurality of entities including a primary entity and a plurality of secondary entities, wherein the entities are text descriptors, a plurality of videos comprising a primary video subset and a secondary video subset, a plurality of web pages comprising a primary web page subset and a secondary web page subset, associations between the primary video subset and the primary entity, associations between the primary web page subset and the primary entity, associations between the secondary video subset and the secondary entities, and associations between the secondary web page subset and the secondary entities; a computer comprising a processor for executing a relatedness engine; a non-transitory computer-readable storage medium storing the relatedness engine, the relatedness engine configured to: determine a first set of co-interaction scores between the primary video subset and the secondary video subset; determine a second set of co-interaction scores between the primary web page subset and the secondary web page subset; determine, using the processor of the computer, a relatedness score between the primary entity and each of the secondary entities, the relatedness scores based on the first and second sets of co-interaction scores; and rank the secondary entities according to their respective relatedness scores.
11. A system comprising: a database configured to store: a plurality of entities including a primary entity and a plurality of secondary entities, wherein the entities are text descriptors, a plurality of videos comprising a primary video subset and a secondary video subset, a plurality of web pages comprising a primary web page subset and a secondary web page subset, associations between the primary video subset and the primary entity, associations between the primary web page subset and the primary entity, associations between the secondary video subset and the secondary entities, and associations between the secondary web page subset and the secondary entities; a computer comprising a processor for executing a relatedness engine; a non-transitory computer-readable storage medium storing the relatedness engine, the relatedness engine configured to: determine a first set of co-interaction scores between the primary video subset and the secondary video subset; determine a second set of co-interaction scores between the primary web page subset and the secondary web page subset; determine, using the processor of the computer, a relatedness score between the primary entity and each of the secondary entities, the relatedness scores based on the first and second sets of co-interaction scores; and rank the secondary entities according to their respective relatedness scores. 12. The system of claim 11 wherein each video in the second video subset is associated with at least one of the secondary entities, and each web page in the second web page subset is associated with at least one of the secondary entities.