I only heard a bit of the Sproul audio and lost interest though maybe I'll listen again later. So I didn't hear him say anything about chance being a power and all that. When he says there is no such thing as chance, though, without going through all the reasoning for it, all he's saying is that nothing happens without God. Which I believe. As for all the complexities that go into the final outcome that we call chance, seems to me that either all of them are chance or all of them are God.
But that's me, not Sproul as far as I know.
But then rading through your post, which I should probably read more carefully some time, it almost sounds to me like you are objecting to the idea of chance, and are ALMOST saying, well, not that nothing happens without God exactly since you don't believe in God, but something close to that -- something along the lines of there being reasons for various stages of a complex event that we cannot know, and the only reason we call the end result chance is that we can't know the stages. But you know there is a "reason" for all of them even though we can't know it.
That's perilously close to saying notning happens without God it seems to me.