Even though there are some replay softwares for PC such as LoLreplay, there is non for Mac. However theres still a way for us mac users to make league content without lol replay, I'm not gonna explain how all of this works, but I'll show the simple step-by-step.

You will need:

• A Macintosh Device iMac/Macbook (No sh*t)
  
• Internet
  
• Terminal
  
• Recording Software
  
• Luck
  

Instruction:

1. Open LOL & enter in a game.
   
2. During Character Select, open up your web browser. Type in op.gg and access to their website.
   
3. Enter in your summoners name
   
4. Once the game is in the Loading Stage, go back to op.gg click "Ingame Info." There should be a record button Click It.
   
5. Now play your game, after the game is done check back in op.gg It'll take awhile (roughly 5min.) for the replay to be available for download.
   
6. After the wait hit Renew Data, a replay icon should be available on the side for you to download... Download it!
   
7. Open up Terminal (Application>Utilities>Terminal)
   
8. Change the file name from .cmd to .sh
   
9. Open up the sh. file copy and past everything in terminal then hit enter
   
10. Boom there you go now record whatever your heart desires.
    

(optional: You can adjust the settings)
(note: sometime op.gg will work and sometime it won't cause of server issues.)