V: The Original Mini Series (1983) - DVD - used

There was a time in the 1980's when the network mini-series' dominated TV, but very few really blew up like the 3 plus hour sci-fi epic V. 

Without giving too much away it's a simple premise. Aliens land on Earth in a big way, and they very suspiciously look like us. They claim they simply need our help, but pretty soon it is realized that there is more to it than that.

Fun fact: A pre "Freddy" Robert Englund appears in this, and it was quite possibly the gig that helped him end up on Elm Street.