(On a sidenote, I bet the creators would have loved to have this run inside the browser; the fact that this cannot be done again shows how broken the web is).
(We actually never thought of building it for the web up to now. The Image Processing community mostly still write in C++ to be able to optimize the code to the bare metal. But it seems that there are solutions emerging (ASM.js and cohorts) for the broken web.)
I wouldn't say the web is broken it's just not up to such a demanding task, yet. SIMD.js should be in Ecmascript 2016 (JS7). Once available, traditional image, audio and video processing techniques should be viable on the web.
(On a sidenote, I bet the creators would have loved to have this run inside the browser; the fact that this cannot be done again shows how broken the web is).