This very nicely done demo video is for the Electro-Harmonix Riddle - an envelope filter fine-tuned for guitar frequency response.
In the video, Jack Conte does a great job of both demonstrating the range of the Riddle and exploring it within a musical context.
Here's the rundown on the Riddle's features:
More From: ELECTRO-HARMONIX
Compact, desktop, analog, semi-modular - whats not to like?