$ curl cheat.sh/
# To download a video in 720p MP4:
youtube-dl -f 22 example.com/watch?v=id

# To download a video in 720p MP4 or WebM or FLV:
youtube-dl -f 22/45/120

# To list all available formats of a video:
youtube-dl -F example.com/watch?v=id

# To download a video to /$uploader/$date/$title.$ext:
youtube-dl -o '%(uploader)s/%(date)s/%(title)s.%(ext)s' example.com/watch?v=id

# To download a video playlist starting from a certain video:
youtube-dl --playlist-start 5 example.com/watch?v=id&list=listid

# To simulate a download with youtube-dl:
youtube-dl -s example.com/watch?v=id

# To download audio in mp3 format with best quality available
youtube-dl --extract-audio --audio-format mp3 --audio-quality 0 example.com/watch?v=id

# For all video formats see link below (unfold "Comparison of YouTube media encoding options")
# https://en.wikipedia.org/w/index.php?title=YouTube&oldid=723160791#Quality_and_formats

# youtube-dl
# Download videos from YouTube and other websites.
# More information: <http://rg3.github.io/youtube-dl/>.

# Download a video or playlist:
youtube-dl 'https://www.youtube.com/watch?v=oHg5SJYRHA0'

# List all formats that a video or playlist is available in:
youtube-dl --list-formats 'https://www.youtube.com/watch?v=Mwa0_nE9H7A'

# Download a video or playlist at a specific quality:
youtube-dl --format "best[height<=480]" 'https://www.youtube.com/watch?v=oHg5SJYRHA0'

# Download the audio from a video and convert it to an MP3:
youtube-dl -x --audio-format mp3 'url'

# Download the best quality audio and video and merge them:
youtube-dl -f bestvideo+bestaudio 'url'

# Download video(s) as MP4 files with custom filenames:
youtube-dl --format mp4 -o "%(playlist_index)s-%(title)s by %(uploader)s on %(upload_date)s in %(playlist)s.%(ext)s" 'url'

# Download a particular language's subtitles along with the video:
youtube-dl --sub-lang en --write-sub 'https://www.youtube.com/watch?v=Mwa0_nE9H7A'

# Download a playlist and extract MP3s from it:
youtube-dl -f "bestaudio" --continue --no-overwrites --ignore-errors --extract-audio --audio-format mp3 -o "%(title)s.%(ext)s" url_to_playlist

Follow @igor_chubin cheat.sh