Yesterday and today, the SyFy channel is running a Twilight Zone marathon. One episode we saw last night (To Serve Man in the clip above) involves an Alien invasion, the inept U.S. military, an arrogant scientist (Lloyd Bochner) and his bombshell assistant (Susan Cummings). The Aliens (Richard Kiel) at first appear altruistically motivated. They leave a book written in their language that is eventually decoded by the bombshell assistant. She first gets the title "To Serve Man" and then figures out what the rest of the book is about to create the surprise ending.
This is all pretty much fun and is considered one of the best Twilight Zone episodes. More information about the Twilight Zone and its creator, Rod Serling, are worth a quick read.