ytdl http:https://www.youtube.com/watch?v=_HSylqgVYQI > myvideo.flv

Usage: ytdl <url> [options]

url     URL to the video.

Options:
   -v, --version                  Print program version.
   -q ITAG, --quality ITAG        Video quality to download. Default: highest
   -r INT-INT, --range INT-INT    Byte range to download. ie 10355705-12452856
   -o FILE, --output FILE         Where to save the file. Default: stdout
   --filter-container REGEXP      Filter in format container. Default: -o ext
   --unfilter-container REGEXP    Filter out format container.
   --filter-resolution REGEXP     Filter in format resolution.
   --unfilter-resolution REGEXP   Filter out format resolution.
   --filter-encoding REGEXP       Filter in format encoding.
   --unfilter-encoding REGEXP     Filter out format encoding.
   -i, --info                     Print video info without downloading
   --print-url                    Print direct download url

[sudo] npm -g install ytdl