Removing spacing issues below the video

Notes: The CSS changes go slightly above and beyond what is required for the fix, however there should not be any unwanted side-effects from the changes

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Changes: 
* Dropping all margins and padding to zero
  The `HTML` and `BODY` elements usually have additional margins, dependent on the user agent.
  This avoids issues that causes.
* Changing the `inline-block` source and video tags to display as `block`