To help those possibly getting their vids from youtube, i shall give a short tutorial
First, go here
Click me and download the file converter.
Then once the file converter is downloaded, open up youtube, find a video you want and open it.
Copy the url of the video from the info box on youtube and open the file converter.
Once the file converter is open, select where you want to save the file too {output folder} and then paste the link into the yellow box and click start.
Depending on the size of the vid it shouldn't take too long.
Once downloaded, open your gif making programme, open the video you've just downloaded and shazam you'll be making gifs in minutes
Or you can find what Simon has as i've not heard of it.