Too many simultaneous streams caused many people not to be able to see the President Obama's Inauguration real-time. CNN.com served a record 21.3 million streams, with a peak of 1.3 million simultaneous streams. Akamai which provides Web Application Acceleration and Performance Management reported a peak of 5.4 million simultaneous visitors per minute to the various news sites that it hosts video for, and more than 7 million simultaneous streams.
It was a huge test for live video streaming, but alas it failed. CNN.com bumped many viewers into virtual waiting rooms until the feed became available. Many people had to keep hitting refresh, unfortunately this would cause you to miss the speech. Many different sources such as Hulu, and Akamai had the same problems.
Because of limitations the Internet can't handle much more than a million simultaneous streams as of now. The superbowl or other large events have many more viewers than that.