Movies on TV

So riddle me this: why does watching a movie on TV take 45 minutes to an hour longer than simply watching the DVD? Commercials. That's why. But why are they so many commercials? Why do TV channels find it necesary to play 45 minutes of 30 second long advertisements? I know it's technically to "make money" but if they're really that hard-pressed for money, should they even be trying to play that movie? Should they even have a TV channel at all?! Snow White and the Seven Dwarves came on TV tonight...it is 83 minutes long; the TV version was 120. Lord of the Rings 3 is 3 and a half hours long by itself...the TV version was 5 hours!! WTF WHY?!? I guess it's just how life works and I'll probably never understand...