Om had a recent post on the rising power of YouTube and it’s dominance over other sites:
For instance, YouTube’s market share of Internet visits has increased 110% over the past three months (week ending May 27 versus week ending March 4, 2006). Yahoo! Video has increased its market share of visits 22% for that same time period. You Tube usage metrics are ahead of Yahoo. For April 2006, YouTube’s average session time for that month was 15 minutes 33 seconds. Yahoo! Video’s average session time was 15 minutes 13 seconds.
Let’s assume that the average “YouTuber” visits the site twice daily (a big stretch, I think). That means the average user spends about a half an hour/day on YouTube. While this number is impressive, the 4 hours and 52 minutes that people spend watching TV on an average day is more impressive. It’s going to take a long time for broadcast to be replaced by Internet delivered video. They're going to both coexist and they're going to play nice together at some point.