Analysis International just released data that shows Youku, Tudou and Sohu share the top 3 positions for the online video advertising market for the second quarter of 2011.

Youku has the strongest lead with 23.4% advertising revenue market share, Tudou has 14% and Sohu has 13%. Over the previous quarter, Youku gained 1%, Tudou dropped from feeling the rising pressure from Sohu. Positions have remained unchanged. This explains Youku being able to pull further away from Tudou in terms of revenue.

Of the tier 2 online video sites, Xunlei has the 4th largest user based and has strong adverting sales revenue. Qiyi is also aggressively growing its content and sales. However Ku6 has recently replaced their CEO, downsized their sales team and shifted strategy. Such big changes have taken them out of any leadership contention.

Since operating an online video site requires huge amounts of capital, unlisted companies can either raise money or stay alive by acquiring popular quality content to attract more viewers to sell more ads.