The authors of the blog don't say, but here's one approach: http://wordpress.mrreid.org/moviebarcode/

A discussion using mplayer for faster output is also attached at http://projects.metafilter.com/2996/Make-your-own-Movie-Barc...

Given the letter artifacts in "Kill Bill" it looks like they're preserving vertical position. So, possibly making each vertical pixel stripe a horizontal average of several consecutive frames---all pixels at height y in an adjacent batch of a few dozen frames.

AviSynth Script http://forum.doom9.org/showthread.php?p=1480852#post1480852

If I was to do it I would take every digital frame and then take each pixel from top left to bottom right and make one long chain. Either that or average x neighboring pixels to fit the size vertically. I have no idea how they did this specifically though.

I think it takes the dominant color from each scene. You can probably do that by resizing each frame to a 1x1 px image.

I'd love a script that takes a batch of movies, feeds them to ffmpeg or something and slowly makes barcodes for my movie collection.