YouTube makes enough money to support itself and not just serve as a marketing instrument for Google

 
YouTube’s bottom line gets a lot of ink, considering there is virtually no confirmed information about the site’s expenses and revenue. Credit Suisse had made a splash in April by estimating that YouTube could lose $470 million this year, however an infrastructure research firm disputed that report, saying the bank had underestimated Google’s ability to minimize costs.
As for the percentage of video views that YouTube monetizes, Rosenberg gave Google’s first real comment on the matter — if only on a relative basis. A YouTube exec had previously said that the assertion that YouTube only monetizes 3-4 percent of views is “grossly inaccurate.” The company gave the slimmest of indications that the portion was at least 9 percent of views, and perhaps higher. In those single digits, tripling might not be as huge of a jump as it seems.
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http://newteevee.com/2009/07/16/google-youtube-will-soon-be-very-profitable/