Afaik, it was a deal that Jobs made (with some other parts) because Microsoft had been found to have code in its Windows' video software that came from Quicktime.
I googled this:
http://www.zdnet.com/blog/apple/stop-the-lies-the-day-that-m...
- Then Steve Jobs himself. I think these specifics support my initial comment.
"If we want to move forward and see Apple healthy and prospering again, we have to let go of a few things here. We have to let go of this notion that for Apple to win, Microsoft has to lose. We have to embrace a notion that for Apple to win, Apple has to do a really good job. And if others are going to help us that's great, because we need all the help we can get, and if we screw up and we don't do a good job, it's not somebody else's fault, it's our fault. So I think that is a very important perspective. If we want Microsoft Office on the Mac, we better treat the company that puts it out with a little bit of gratitude; we like their software. So, the era of setting this up as a competition between Apple and Microsoft is over as far as I'm concerned. This is about getting Apple healthy, this is about Apple being able to make incredibly great contributions to the industry and to get healthy and prosper again."
Again, this is an old subject. Google "video for windows" "source code" apple quicktime
E.g.
http://en.wikipedia.org/wiki/Video_for_Windows#Overview
"In 1995, Video for Windows became an issue in a lawsuit Apple filed against Microsoft, Intel, and the San Francisco Canyon Company, regarding the alleged theft of several thousand lines of QuickTime source code to improve the performance of Video for Windows.[3][4][5][6] This lawsuit was ultimately settled in 1997, when Apple agreed to make Internet Explorer the default browser over Netscape, and Microsoft agreed to continue developing Office and other software for the Mac for the next 5 years, and purchase $150 million of non-voting Apple stock."