Yes, but this is only 1 among many other fundamentals such as stance, stroke, aim, etc. All fundamentals can account for 25% of your success as a pool player.
My point is, use these free resources first and develop yourself into a complete player who can actually play. Then the next step is to start mastering each individual fundamental or component: vision center, stance, stroke, aiming, cue-ball control, etc. Now you can PAY to learn more...
Next step is practice - 50%. Without practice, a Harvard student with no experience can't beat a home-school dude with 5 years of actual experience in any trade or field.
Final step is your mental - 20%. Weak mental can't win anything.
Luck: 5%.
You are now 100% ready to play in APA.