How to turn a movie file into a GIF?

I took video on my camera (Nikon D5000) and I'd like to turn that video into a GIF file that runs on a constant loop. Sort of like a time lapse. The video in specific is a sunset sort of thing and it's about 15 minutes long, but I'd like to condense and speed it up, and set it on a constant dark-bright-dark-bright sort of thing. Does anyone know how I can do this?

The best way would be to use adobe flash.

How Tos (Animation):

How to Make a Animated GIF from a Video Clip:
How to Convert a Video Into a Gif Animation: http://www.wikihow.com/Convert-a-Video-Into-a-Gif-Animation
Easy to Use Video to GIF Software: http://www.video-gif.com/ [not free]
Video-AVI to GIF/JPEG Converter (Price: Free to try (Watermark on output); $19.95 to buy. http://download.cnet.com/...79741.html

GIF Animations Instructions: http://www.frontiernet.net/~steve_glimpse/animinst.html
How to create an Animated gif (Video):
How to Create Animated GIFs Using Photoshop CS3: http://www.wikihow.com/Create-Animated-GIFs-Using-Photoshop-CS3