[pj]

abl, you are missing the point.

None of the features of the services you mention are "difficult" to do. PageRank is very easy. The scale is difficult, but lots of companies can scale too. How many YouTubes are there? How many social networks are there?

The issue here is that YouTube continues to improve. They never stop. They just recently "knocked off" the "turn down the lights" feature at Hulu. They could have said, "aw forget it, no one likes turn down the lights" and refused to implement it.

YouTube continues to run hard and fast. That's why they continue to be the winner. If they stop and they don't give their users a constantly improving product that matches the rest and betters the rest, then youtube will cease to be the leader.