In this tutorial, I explain how you can access the separate GIFs, videos or other media that are contained within a PowerPoint or Slides file: goo.gl/Awkjhg. Check it out!
When I upload the files to Drive, I usually use the technique explained here: goo.gl/BtYzMf to rename the files with a filename that describes the file.
Don't forget to get permission and credit the person who is featured in and/or shared the original file!