Default Value for Current Mastery Progress

Purpose Driven.
vno no longer is used as a reference to the object number in the array. --> vno is now use to checked against the value of video.no , and now retrieve video if match.

Mastery
Error if user has no records. --> implement try catch , if catch err , will default coach to zandar, and path name and path Id to the first element derived from player_progress API.