NOTE: This tutorial is meant for Bootstrap theme 3.0. If you install the newer version 3.1 and above, you can watch the new videos recorded here to see how to create sub theme for 3.1 and above.
Tutorials for Bootstrap Theme 3.1 and above:
https://goo.gl/440JSN
You can then skip few tutorials in this series and proceed to - Tutorial 6 - Getting template files ready.
https://goo.gl/ZtOcKe
On this page of the site you can watch the video online Drupal Bootstrap - 4 - Creating Bootstrap Sub Theme with a duration of hours minute second in good quality, which was uploaded by the user Drupal Legoland 05 October 2015, share the link with friends and acquaintances, this video has already been watched 31,434 times on youtube and it was liked by 58 viewers. Enjoy your viewing!