Useful link:
Newhart, the Norm Show, the Adventures of Pete and Pete … and others.
I fell down the rabbit hole and ended up in Norm Wonderland.
Seven Solidly Funny Sitcoms Whose Full Runs Are Only Available on YouTube
Other Crap
Uncle Scoopy's world-weary musings about naked celebrities, sports, humor and other important, manly things.
I remember one thing from the Norm show.
He told someone that the cross on their desk was offensive because some people worshipped a guy who was crucified on one of them.
The Bob Newhart Show ($36.98), Newhart ($56.99), and Bob ($11.92) complete series are available on DVD on Amazon. That would seem like the only way to make sure you always have access to a series or movie, but only until DVD rot makes those discs unplayable. Really, the only way to be sure you will always have access to a video is to either rip it to your computer or download them via a torrent site.
With all that said, if you can’t find a program available anywhere else, you will probably be able to find it on YouTube. Whenever I am feeling nostalgic for a TV show from my childhood, I will probably be able to find it there.