WordPress.org

Does it show only posts ?

Yes, no comment or page or something else...

Can I include it in a post ?

Yes, since version 0.2

What happends if I don't have Popular Posts?

Nothing wrong happends, the page stays blank without error.

Does it works with others similar plugins ?

Not yet, but if you let me know about a plugin and his get_post_views($post_id) function,
I will add it in future versions of boxoffice

Why is your english so bad ?

Because I'm French!