As the internet increases in speed and we come closer and closer to the ability to process more calculations dealing with polygons and 3D (x,y,z) redering, we become more capable at turning the net into a place where streaming video takes the place of television which offers the level of interaction only dreamed up with a regular television set. 

VOIP (voice over Internet Protocol (or just a way for the sound card to read your data)) has allowed for the telephone to now become a video found as we are able to send video signals as well as audio signals.  Since we can send video signals, we can provide a way to stream (download just enough for continous showing of a video without downloading the entire thing) a television show or an entire movie.  The television show or movie will not be downloaded to a person pc to a degree and they get just enough to let the person see the movie and at the same time have the movie protected where the authors of the movie can afford to make another one.

The point is the codec (compressor/decompressor, um, video encrypted or compressed format) needed to view the movie comes in several desent formats.  Unfortunately if you want to view a movie on a public or just any computer that isn't yours, you have to figure out which codec they are using.  Common are Real, Windows Media and quicktime.  Others are designed to ensure the 3 affore mention codecs don't dominate the net and make only their players the only codecs available to view a movie.  The would mean you would have to pay for their codecs and they could monopolize the internet tv business.  Not really due to programmers like me but hey, it's a theory.

So, before internet tv becomes a reality, there must be some type of codec that someone won't cry copyright infringement the moment someone trys to bundle it with their browser.