What's your opinion on using other peoples videos and photography to create art?

Here is some stuff I have in mind:

1. Imagine watching an animal documentary on Youtube and then making a screenshot of a lion, that's staring into the camera. And then taking that screenshot and then using it in Photoshop to create art.
2. Imagine picking a the simple image of an action figure, which is being sold on Amazon and then using various Photoshop filters or Illustrator vectorization to create art.
   

And I could go on and on with the examples. Obviously it would never be about taking other peoples art and then using bits and pieces of it in the own art. This is more about that grey area, where copyright claims just wouldn't make much sense. I'm still unsure as how to feel about it.

Great design resource

100 Things Every Designer Needs to Know About People (Voices That Matter) Submitted April 09, 2019 at 10:44PM by Voidsentry http://bit.ly/2I6WF0w