There are countless tutorials on YouTube covering this subject, but the only one that really stuck out to me was nst's tutorial.  
https://www.youtube.com/watch?v=0Dmhd17QISI  
The video in your question doesn't necessarily represent the true nature of the game as you will zoom out after each shot.  
nst does a good job at covering how to predict player movement, sniper v sniper, "doublezooming" and class priorities among others.