[downloader/ffmpeg] Support for DASH manifests (experimental)

Closes #159

yt_dlp/utils.py

@@ -4987,6 +4987,7 @@ def cli_configuration_args(argdict, keys, default=[], use_compat=True):
             return [arg for args in arg_list for arg in args]
     return default
 
+
 def _configuration_args(main_key, argdict, exe, keys=None, default=[], use_compat=True):
     main_key, exe = main_key.lower(), exe.lower()
     root_key = exe if main_key == exe else f'{main_key}+{exe}'