What can I do with this generator?
You can make watermark-free animated gifs online.
What sources can I make gifs from?
Why can't I use a video or set of images larger than 20MB?
Bandwidth is a very expensive commodity, and this app will always be free. At some point there may be a more robust paid version, but not today. If you are serious about making quality GIFs with large media files, you need to be doing it with software on your own computer anyway.
How can I make my GIFs generate faster while maintaining quality?
Every option except for "speed" will make GIF creation slower when you crank it up. However, you can make all creations faster if you minimize the length of the original video, and if you use videos whose size is similar to your final GIF. So don't upload a full HD video, and then expect a 200x200 2 second clip to generate quickly.