1. A method performed by a data processing apparatus, the method comprising: determining video resources hosted on devices assigned to a domain; for each video resource determined to be hosted on the domain, determining a quality metric for the video resource; generating a quality score from the quality metrics for video resources hosted on the domain; generating a quantity score based on counts of video resources hosted on the domain, the counts including: a first count of video resources hosted on the domain; and a second count of resources hosted on the domain that are determined to include a video resource; determining a domain video score from the quality score and the quantity score; and adjusting, based on the domain video score, one or more video search operations on the video resources hosted on the domain.