I don't know who KSI is, but from what the Internet tells me, he's quite the misogynistic douchebag that sexually harassed female event goers at Eurogamer Expo 2012. He's been banned from all Eurogamer events as a result. He was oddly chosen as one of the performers scheduled for the Xbox One launch event in London. Afterwards, he filed a YouTube copyright claim against a journalist that questioned Microsoft's decision to hire a huge douchebag for their event. A "copyright safe" version of the video can be found below.

Microsoft was apparently unaware of KSI's "exploits" when they hired him for the event. Needless to say, most anybody with even a shred of common decency (and who know who KSI was beforehand (which doesn't include me)) became quite upset with the company for their decision. Microsoft has responded by severing all ties with KSI, though they did so after he already performed at their event.

When questioned about Microsoft's decision to hire KSI, Phil Harrison responded that he was "not familiar with the concerns raised."

(via GI.biz)