There are shares out there in the market. Most of those shares are held by MM's. That is how they keep the market liquid. Not all of the shares are held by them, people like you and I make up a significant amount of the remainder. The MM's make money on every trade. When the company buys back shares from them it reduces the amount of outstanding shares in the market place and this adds value to the shares that you and I have held through this process. The MM's will "hold" the price at a prearranged level in return for the company buying so many shares from them.
Thats about it. It's the way our markets work and it's what makes it such a great place to be able to make money!!! Downside is, you can lose money too if you aren't careful!!!
"Sort of" is such a harmless thing to say. "Sort of". It's just a filler. "Sort of" - It doesn't really mean anything. But after certain things, "sort of" means everything. Like after "I love you" or "You're going to live" or "It's a boy".