1 install rabbit-youtube via. pip
bash-3.2$ pip install rabbit-youtube
    Collecting rabbit-youtube
    Installing collected packages: rabbit-youtube
    Successfully installed rabbit-youtube-0.1.1
bash-3.2$ rabbit-youtube.py
    no config file found, please input your google api key:
            
you'll need a Google API key to setup the application.
2 Get a Google API key
Login to Google developer console (https://console.developers.google.com/apis/credentials):
"Add credentials" > "API key" > "Browser key" > give it a name and "Create"
You may copy the newly created "key" to rabbit-youtube now:
bash-3.2$ rabbit-youtube.py
    no config file found, please input your google api key:$key
    usage: rabbit-youtube.py [-h] [--youtube_user_id YOUTUBE_USER_ID]
                         [--playlist_id PLAYLIST_ID]
                         download_to
    rabbit-youtube.py: error: too few arguments
3 Ready to use!
bash-3.2$ rabbit-youtube.py -u ChromeDevelopers /tmp/test/
    going to download all videos uploaded by user_id: ChromeDevelopers to: /tmp/test/
    downloading videos by user_id :ChromeDevelopers
    22:17:27 [rabbit_youtube.youtube_utils] [INFO ]  videos found: 122
    22:22:41 [rabbit_youtube.youtube_utils] [DEBUG]  best video found for: YBNBr9ECXLo - Unit Testing with Web Component Tester -- Polycasts 36
    22:22:41 [rabbit_youtube.youtube_utils] [INFO ]  downloading file: YBNBr9ECXLo_Unit Testing with Web Component Tester -- Polycasts 36_720p.mp4
    ...
    22:21:12 [rabbit_youtube.youtube_utils] [INFO ]  file existing in the destination folder: /tmp/test/ChromeDevelopers/UUnUYZLuoy1rq1aVMwx4aTzw/1F07jdLE2Ds_Totally Tooling Tips - Cross Device Testing (S2 Ep6)_720p.mp4. will not download it again.