%(upload_date)s for the upload date (YYYYMMDD),
%(extractor)s for the provider (youtube, metacafe,
etc), %(id)s for the video id and %% for a literal
%(upload_date)s for the upload date (YYYYMMDD),
%(extractor)s for the provider (youtube, metacafe,
etc), %(id)s for the video id and %% for a literal