Use youtube-dl to download all videos from a YouTube user, rename with consistent naming scheme, add/embed thumbnails and metadata
youtube-dl https://www.youtube.com/user/ohbutyes/videos --format mp4/flv/3gp --output '%(title)s___YouTube_video_id_%(id)s___uploaded_by_%(uploader)s___uploaded_%(upload_date)s___%(resolution)s.%(ext)s' --restrict-filenames --write-sub --write-description --write-info-json --write-thumbnail --print-traffic --verbose --embed-subs --embed-thumbnail --add-metadata --xattrs