If you want to know what video/audio codec are used for the video file you downloaded from somewhere, you can play the video itself. Most media player software such as VLC or MPlayer can display properties of a video file being played. However, there are command-line utilities that allow you to determine video properties quickly.
In this tutorial, I will describe how to check video formats from the command line on Linux.
Full article here:
How to identify video formats from command line on Linux (Xmodulo)