Question: how to download videos from youtube by changing url?
Answer: Tip #1: Change YouTube to ssyoutube. youtube.com/watch? v=C6MVEwl0ceI&t=2s -> ssyoutube.com/watch? ... 
Tip #2: Change YouTube to youpak. youtube.com/watch? v=C6MVEwl0ceI&t=2s -> youpak.com/watch? ... 
Tip #3: Insert "pp" after "youtube" youtube.com/watch? ... 
Tip #4: Add "pwn" before "youtube" youtube.com/watch?