Despite massive viewing figures, online television has yet to achieve commercial success, according to new research.

TV analysis firm ThinkBox says that it's proving difficult for TV channels to make revenue from online catch-up services such as the BBC's iPlayer and Channel 4's 4oD.

However, ThinkBox reports that revenue generated from traditional TV is on a high with 2.5 billion adverts being viewed in the first half of 2008. Nonetheless, ThinkBox believes the two mediums can happily co-exist.

"Online TV services are primarily used as a means of catching up with the broadcast stream."

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