Added --remux-video option

Fixes #6996

- Supported formats declared: mp4, mkv
- Added FFmpegVideoRemuxerPP as postprocessor
- Added option to README and shell-completion scripts

devscripts/fish-completion.py

@@ -14,6 +14,7 @@ FISH_COMPLETION_FILE = 'youtube-dl.fish'
 FISH_COMPLETION_TEMPLATE = 'devscripts/fish-completion.in'
 
 EXTRA_ARGS = {
+    'remux-video': ['--arguments', 'mp4 mkv', '--exclusive'],
     'recode-video': ['--arguments', 'mp4 flv ogg webm mkv', '--exclusive'],
 
     # Options that need a file parameter

devscripts/zsh-completion.in

@@ -16,6 +16,8 @@ __youtube_dl() {
                 _path_files
             elif [[ ${prev} =~ ${diropts} ]]; then
                 _path_files -/
+            elif [[ ${prev} == "--remux-video" ]]; then
+                _arguments '*: :(mp4 mkv)'
             elif [[ ${prev} == "--recode-video" ]]; then
                 _arguments '*: :(mp4 flv ogg webm mkv)'
             else