This will (hopefully) be a thread for us to share our knowledge. Feel free to ask questions; with any luck, another savvy Mutant will have the answers for you!
To start us off:
This is how I extract gifs using a phone/tablet. It’s probably not much different using a computer:
Long-press on the gif you want to grab until the bar with Copy GIF Address appears. Click on it to save the GIF address to your Clipboard.
Navigate to EZGif.com’s Video-to-GIF Converter, and paste the address into the OR paste video URL box. Hit the Upload Video! button.
At this point I usually play through the video to make sure the endpoint is set properly. If you like, you can also adjust the size of the graphic-- longer or larger videos tend to make larger GIFs. If you’re all set, hit the Convert to GIF! button.
Once the GIF is loaded, you can save it to your phone/tablet/computer in the usual way. If it winds up too large to post, you can select Resize or Optimize for compression options to make the file smaller.
Please note that this will NOT work on Twitter videos. EZGIF will generate an error message if you attempt to grab a video in this manner. There is a way to save videos, which I can post if there’s interest.