Systems and methods are provided for supplying a video advertisement to a web page or application. A main ad server provides an ecosystem to network ad servers from different ad networks. The main ad server can collect and store information about each of the demand tags associated with each of the network ad servers in a database. The main ad server can then review the database in response to an ad call from a publisher to generate an ordered list of the demand tags that correspond to the ad call. The main ad server can then determine if any of the demand tags in the ordered list has a corresponding video header bidding tag and initiate an auction process for all of the demand tags in the ordered list that have a video header bidding tag. The ordered list of demand tags can then be updated based on the results of the auction process.