Public performance when it comes to the internet

As promised I did a little digging into how the idea of public performance plays out on the internet. I checked NBC's site, and it says "Such material is protected by copyright, trademark, and other applicable laws. You may not modify, copy, reproduce, republish, upload, post, transmit, publicly display, prepare derivative works based on, or distribute in any way any material from the Site, including but not limited to text, audio, video, code and software."

So it looks like as far as the non-cable stations are concerned, public performance copyright still stands even if its a streaming online video. When it comes to cable sites, such as Discovery, their site states, that materials are "protected by copyright, trademark and other intellectual property laws. You are free to display and print for your personal, non-commercial use information you receive through the Discovery Sites. But you may not otherwise reproduce any of the materials without the prior written consent of the owner. You may not distribute copies of materials found on the Discovery Sites in any form (including by e-mail or other electronic means), without prior written permission from the owner."

So again the law still stands when it comes to the internet, but what about Utube? How does copyright law relate to that site, I wonder?