Q: Why does one need to worry about processing power for a video? VR, perhaps?
A: you need to worry about processing power for anything you do on a computer. the more processing power you have, the faster you can do the task. some tasks like word processing are handled perfectly fine by most computers. but when it comes to making videos, especially videos with multiple things that move, it can take more time.  if you had an infinite lifetime you would not have to worry about this.