I did it 5 times:
1st try: LeBron to Heat with Wade, we get NO ONE (lol)
2nd try: Lebron stays in Cleveland, we get David Lee (lol)
3rd try: LeBron stays in Cleveland, we get Bosh
4th try: LeBron to the Bulls (Bosh to Lakers)
5th try: LeBron to the Bulls, and we also get Joe Johnson
Looks like it's based on odds from ESPN's "experts", so who knows what the probabilities in the machine are. From the results I got, it looks like what we've all been thinking, though - Cleveland or Chicago.