After you see the video, you can visit the National Archives website to read about finding your relatives and ancestors on the 1940 census returns, even before they're indexed. You can start by making a list of parents, grandparents and great-grandparents, and note where they were living in 1930, and where you think they were living in 1940.
Here's my list:
Arnold and Ervilla Stoelt - Detroit, Michigan
Maurice and Ruby Reed - Lansing, Michigan
Henry Hickox Chase - Traverse City, Michigan
Percy and Mary Reed - Beulah, Michigan
Herbert Kenny Randall - Detroit, Michigan
Stacy and Marian Thompson - Manistee, Michigan
Of course, they're just the beginning of the list of people I'll want to find. For all the cousins, aunts and uncles who I've found on the 1930 census, I'll use my genealogy software (Legacy Family Tree) to generate a list. It's as simple as asking it to find everyone who was born before 1940 and died after 1940. My search of my database (with over 3000 names) yielded an 18-page list of over 500 people!
Another thing I'm doing to get ready is indexing for FamilySearch. You can sign up here - it's easy and fun, and contributes to all of us who are searching for our ancestors!