Example 1
Righteous Kill may be a terrible film, but it's one of only two films (along with Heat) where Robert DeNiro and Al Pacino share the same scenes.
In this cinematic sentence, along with Heat belongs in parentheses because it's additional information that, while interesting, isn't essential to the main idea of the sentence.
Example 2
Five Guys (over 1,000 locations nationwide) has built a cult-like following for their mouthwatering burgers and fries.
We firmly believe that barbecue sauce is essential to a Five Guys bacon burger. In this particular example, the number of locations Five Guys has is not essential to the main point of the sentence. Therefore, it belongs in parentheses.