put https://api.jwplayer.com/v2/sites//channels//events//request_master/
Allows you to add temporary access to the master (highest-quality) version of the asset in MP4 format. A URL is created that can be used to download the master version for 24 hours. After 24 hours, master access is no longer available.
Making the master available is an asynchronous process. The status of the request is represented in the master_access property of the response object for a live channel event. Master access can only be requested after a stream has ended.