Hinduism: Monotheistic or Polytheistic?

Teaching Hinduism?  Is it a monotheistic religion or is it a polytheistic religion? 

Here's an excellent short clip about the concept of God in Hinduism developed by the magazine, Hinduism Today and the Hindu Students Association.  It explains Hinduism as a monotheistic religion in which Hindus believe in "one all-pervasive supreme being who is both immanent and transcendent."