I rewrote a much played with Processing sketch to openFrameworks. This shows a way to do a vertical slit scan (Left / Right) on a live video feed.
This software is only tested on Mac OS X Yosemite and the 0.8.4 release of openframeworks.
Download openframeworks (http://openframeworks.cc). Create a new project via the recommend way (http://openframeworks.cc/tutorials/introduction/001_chapter1.html).
In the new project folder replace the src/ directory with the one given here.
p.s There is a little bug still where with certian settings applied a none scanned portion of video will occure. Working on it.