create online YouTube 1080p Downlaoder script

I need simple single page Online YouTube 1080p downloader script which use youtube-dl, ffmpeg or any well knows ultra fast converting plugin, Script will download only 1 format 1080p as a single .mp4 file //------------------------------------- We need this script for our browser extension so script will detect YouTube video from its link example1: [login to view URL] //------------------------------------- Add progress bar which show percentage of conversion, //------------------------------------- script will show error, success, warnings notification. //------------------------------------- from script we will set max video length limit. //------------------------------------- Use simple and fast code. //-------------------------------------- NOTE around 3 year ago, YouTube switched from the "single file stream", to "DASH" streaming, which streams the video and the audio to you as two separate streams, which are played in sync with each other in the YouTube player. You need to combine that Video and audio in one file and provide it for download..