What is “qtfaststart” Package?

Utility for Quicktime files
For more details: https://libav.org/

Installation

• Open Terminal by pressing command+space then type terminal and hit Enter key.
• Install homebrew first.

  ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null

• Install qtfaststart.

  brew install qtfaststart

Now, use qtfaststart!