The link on the video says they used magic lantern which is alternate firmware update that is open source for the t2i and other canon bodies. I can only say that canon will not support it, it can void your warrenty, and overheat and cause all sorts of shut down problems. Having said that, this is how they were able to adjust the shutter setting slower. I have also seen some amazingly high speed slow mo stuff shot progressive speed ramped to look like arri alexa. Amazing.
Here is my take on it, I am a pro video with 18 years of broadcast. Personally I would not try ML on my t2i until I get a better camera and this guy becomes no issue for me as a backup body. The issue with these canon cameras as video cameras lies in the fact that the processor used to backhaul the data is not optimized for video, it is optimized for great stills, stunning in fact. Video processing although lower res even on 1080 i/p, uses a lot of processing, even more than just getting a 18mp still on raw with AA. Its not even in the same ball park. Processing is heat, and this camera and other canon bodies can overheat even on the regular f/w let alone some of the crazy thing ML will let you do. This is why video has lagged behind film in quality and why a C300 or C500 is thousands of dollars more for a dedicated canon video camera.
Personally I really give magic lantern a lot of credit, they essentially overhauled the system software to give you zebra bars, markers, better shutter, intervolometer etc. I am just not about to try it on my cam since it is still my primary.
For people out there needing a low light solution, check out a EF 1.4 or 1.2 manual focus 50mm lens, it is some of the best glass canon ever made and edge to edge sharp.