Beginning MySQL/Python
Django uses its own ORM, so I guess it's not completely necessary to learn MySQL first, but I suspect it would help a fair bit to know what's going on behind the scenes, and it will help you think in the correct way to formulate your queries.
I would start learning MySQL (or any other SQL), after you've got a pretty good grip on Python, but probably before you start learning Django, or perhaps alongside. You won't need a thorough understanding of SQL. At least, not to get started.

Err... ORM/Object Relational Mapper, it hides/abstracts the complexities of SQL and lets you access your data through the simple objects/models you define in Python. For example, you might have a "Person" model with Name, Age, etc. That Name and Age could be stored and retrieved from the database transparently just be accessing the object, without having to write any SQL. (Just a simple .save() and .get())
I have just begun learning Python. Eventually I will learn Django, as my goal is to able to do web development (video sharing/social networking). At which point should I begin learning MySQL? Do I need to know it before I even begin Django? If so, how much should I look to know before diving into Django? Thank you.