help='video format code, specify the order of preference using slashes: -f 22/17/18 . -f mp4 , -f m4a and -f flv are also supported. You can also use the special names "best", "bestvideo", "bestaudio", "worst", "worstvideo" and "worstaudio". By default, youtube-dl will pick the best quality.')
help='video format code, specify the order of preference using slashes: -f 22/17/18 . -f mp4 , -f m4a and -f flv are also supported. You can also use the special names "best", "bestvideo", "bestaudio", "worst", "worstvideo" and "worstaudio". By default, youtube-dl will pick the best quality. Use commas to download multiple audio formats, such as -f 136/137/mp4/bestvideo,140/m4a/bestaudio')
video_format.add_option('--all-formats',
video_format.add_option('--all-formats',
action='store_const',dest='format',help='download all available video formats',const='all')
action='store_const',dest='format',help='download all available video formats',const='all')