Cacher is the code snippet organizer for pro developers

Instructions

To capture the video (filesize: 19MB), using the free "QuickTime Player" application:

Open "Quicktime Player",
Go to File -> New Screen Recording
Selected screen portion by dragging a rectangle, recorded 13 second video.
Go to File -> Export -> As Movie
Saved the video in full quality with the filename in.mov
To convert in.mov into out.gif (filesize: 48KB), open Terminal to the folder with in.mov and run the following command:

ffmpeg -i in.mov -s 600x400 -pix_fmt rgb24 -r 10 -f gif - | gifsicle --optimize=3 --delay=3 > out.gif
Notes on the arguments:

-r 10 tells ffmpeg to reduce the frame rate from 25 fps to 10
-s 600x400 tells ffmpeg the max-width and max-height
--delay=3 tells gifsicle to delay 30ms between each gif
--optimize=3 requests that gifsicle use the slowest/most file-size optimization
To share the new GIF using Dropbox and Copy Public URL, run the following:

cp out.gif ~/Dropbox/Public/screenshots/Screencast-`date +"%Y.%m.%d-%H.%M"`.gif
Installation

The conversion process requires the following command-line tools:

ffmpeg to process the video file
gifsicle to create and optimize the an animated gif
If you use homebrew and homebrew-cask software packages, just type this in:

brew install ffmpeg 
brew cask install x-quartz #dependency for gifsicle, only required for mountain-lion and above
open /usr/local/Cellar/x-quartz/2.7.4/XQuartz.pkg # runs the XQuartz installer
brew install gifsicle
See also

I ended up rewriting this gist's functionality into screengif, a ruby script with significant quality improvements and a few gratuitous features. Check it out at https://github.com/dergachev/screengif

Resources

http://schneems.com/post/41104255619/use-gifs-in-your-pull-request-for-good-not-evil (primary source!)
http://www.reddit.com/r/programming/comments/16zu7d/use_gifs_in_your_pull_requests_for_good_not_evil/
http://superuser.com/questions/436056/how-can-i-get-ffmpeg-to-convert-a-mov-to-a-gif#_=_
http://gnuski.blogspot.ca/2012/06/creating-animate-gif-with-free-software.html
Related Ideas

Extend https://github.com/dergachev/copy-public-url folder action for this use case
it would automate the conversion before copying Dropbox public URL
assign the folder action to ~/Dropbox/Public/Screenshots/gif
consider finding a way to simplify the dependency installation
 Performance-vs-quality.md Raw
GIF-Screencast-OSX performance testing
I was disappointed with the color and quality that ffmpeg's GIF conversion gives. Imagemagick's convert can also be used to do the conversion, though this has serious performance penalties.

The following details my experiments of converting a 3.8 second movie to a GIF.

FFMPEG to PNG -> CONVERT to GIF individually

42 seconds in CONVERT, did not determine file size
ffmpeg -i in-trimmed.mov -r 10 -vcodec png out-static-%02d.png 
time for img in out-static*.png; do convert -verbose +dither -layers Optimize "$img" "$img.gif" ;  done
FFMPEG to PNG -> CONVERT TO GIF in bulk

70KB filesize; 7.2 seconds in CONVERT
http://dl-web.dropbox.com/u/29440342/screenshots/CTHVGY-Screencast-2013.02.06-18.03.gif
ffmpeg -i in-trimmed.mov -r 10 -vcodec png out-static-%02d.png 
time convert -verbose +dither -layers Optimize -resize 600x600\> out-static*.png  GIF:- > out13.gif
FFMPEG to PNG -> CONVERT to GIF in bulk -> gifsicle

56KB size; 7.2 seconds in CONVERT
http://dl-web.dropbox.com/u/29440342/screenshots/USNVKN-Screencast-2013.02.06-18.13.gif
ffmpeg -i in-trimmed.mov -r 10 -vcodec png out-static-%02d.png 
time convert -verbose +dither -layers Optimize -resize 600x600\> out-static*.png  GIF:- | gifsicle --colors 128 --delay=5 --loop --optimize=3 --multifile - > out12.gif
FFMPEG to PPM -> CONVERT to GIF in bulk

6.7 seconds in CONVERT, 70KB filesize
http://dl-web.dropbox.com/u/29440342/screenshots/ZMMDMX-Screencast-2013.02.06-17.59.gif
ffmpeg -i in-trimmed.mov -r 10 -vcodec ppm out-static-%02d.ppm
time convert -verbose +dither -layers Optimize -resize 600x600\> out-static*.ppm  GIF:- > out14.gif
FFMPEG to PPM -> CONVERT to GIF in bulk -> gifsicle

7.2 seconds in CONVERT, 56KB filesize
http://dl-web.dropbox.com/u/29440342/screenshots/UGTQNY-Screencast-2013.02.06-17.49.gif
time ffmpeg -i  in-trimmed.mov -r 10 -f image2pipe -vcodec ppm - |  time convert -verbose +dither -layers Optimize -resize 600x600\> - gif:- | gifsicle --colors 128 --delay=5 --loop --optimize=3 --multifile ->  out15.gif
FFMPEG to GIF -> gifsicle

1 second total (not using CONVERT), 22KB filesize
http://dl-web.dropbox.com/u/29440342/screenshots/XVXWCJ-Screencast-2013.02.06-17.48.gif
ffmpeg -i in-trimmed.mov -vf "scale=min(iw\,600):-1" -pix_fmt rgb24 -r 10 -f gif - | gifsicle --optimize=3 --delay=7 --colors 128 > out16.gif
Notes

Omitting resizing down to 600x600 before converting to GIF dramatically slows down CONVERT.
PPM is the only image format that is compatible with FFMPEG piping directly to CONVERT
it has the same performance and compression characteristics as outputting to PNG
it avoids creating and cleaning up temporary image files
otherwise the temporary files would need to be sorted by numeric order before globbing
Resources

http://www.imagemagick.org/discourse-server/viewtopic.php?f=2&t=18320#reading-multiple-images-over-standard-input
http://superuser.com/questions/71028/batch-converting-png-to-jpg-in-linux
http://zeekish.wordpress.com/2011/09/14/pdf-to-gif-conversion-and-optimization/
http://stackoverflow.com/questions/3306888/ffmpeg-generate-n-evenly-spaced-png-screenshots
http://mariovalle.name/postprocessing/ImageTools.html#gifsicle
http://ffmpeg-users.933282.n4.nabble.com/Converting-avi-files-to-animated-gifs-td935274.html
https://lists.libav.org/pipermail/ffmpeg-user/2010-August/026860.html
http://stackoverflow.com/questions/8133242/ffmpeg-resize-down-larger-video-to-fit-desired-size-and-add-padding
http://superuser.com/questions/318845/improve-quality-of-ffmpeg-created-jpgs

ffmpeg -i in.mov -s 600x400 -pix_fmt rgb24 -r 10 -f gif - | gifsicle --optimize=3 --delay=3 > out.gif