Added an option to specify an output format for merges when downloading separate video & audio

youtube_dl/options.py

@@ -302,6 +302,12 @@ def parseOpts(overrideArguments=None):
         '--youtube-skip-dash-manifest',
         action='store_false', dest='youtube_include_dash_manifest',
         help='Do not download the DASH manifest on YouTube videos')
+    video_format.add_option(
+    	'--merge-output-format',
+        action='store', dest='merge_output_format', metavar='FORMAT' ,default=None,
+        help=(
+            'If a merge is required (e.g. bestvideo+bestaudio), output to given container format (e.g. mkv, mp4, ogg, webm, flv) '
+            'Ignored if no merge is required'))
 
     subtitles = optparse.OptionGroup(parser, 'Subtitle Options')
     subtitles.add_option(