how do you make .gif's from video again?

i know someone put this up before but i couldn't find anything in the archives (is that search toolbar even functional for GB?) and i just wanted to know how to make a .gif file. for example, how do you get a golden gem of awesomeness like...

...from one of the 1980s most timeless ballads...

...which was thoroughly parodied by the great social critics of the 1990s Beavis and Butthead...

...and then used by President Barack Obama as his entrance music at the 2011 National Correspondents' Dinner (no joke)?

Thanks and Happy Halloween!