If you have "regular" Hulu access (a subscription service that requires a login), watching the documentary may be within Fair Use guidelines, but bear in mind that you may not do the same thing for another class in another semester.
If yours is a Hulu Plus account, you must contact Hulu for permission.
Here are a couple of links that might clarify the law:
As a reminder, I am a librarian and not a lawyer and we are not supplying legal advice nor is this information intended to replace the advice of legal counsel.