Neotorama offers "four hypotheses to explain the awesomeness of this video: 1. A video editor carefully sifted through hours of floor speeches and spliced together the lyrics to Rick Astley's song. 2. The clerks working for the legislators are pulling a huge, well-orchestrated prank. 3. The legislators are reading letters from constituents, who are the true pranksters, into the House record upon request. 4. The legislators themselves are intentionally Rick Rolling their colleagues."
The video was posted first to YouTube on April 1, natch.