Seth Bloom. Photo: AT&T

"We have heard you. We are on it."

So says the Seth Bloom -- a.k.a. Seth the blogger guy -- the geeky talking head that AT&T (T) has sent out to do damage control in the face of rising outrage among Apple (AAPL) iPhone users about the quality of AT&T's service, particularly in urban areas like San Francisco and New York.

(See for example Wednesday's New York Times, which dubbed the data-guzzling iPhone "the Hummer of cellphones.")

Bloom appeared in a series of YouTube videos in June and July when AT&T had good news to share with iPhone users -- that it was extending upgrade eligibility, for example, or auto-authenticating Wi-Fi hotspots. As service deteriorated over the summer, he was silent.

But Seth the blogger guy was back Thursday to let us know that AT&T will enable its Multimedia Messaging Service for iPhone users on Sept. 25 -- a few days after its self-imposed "late summer" deadline, but close enough -- and to explain, with charts and diagrams, that keeping up with the bandwidth demands of all those hard-driving Hummers is really, really hard.

For this video, blogger guy has left Starbucks and the AT&T store behind and moved to a studio, where he does his stand-up before an Apple-style seamless backdrop. But Justin Long he is not. And judging from the tenor of the comments on YouTube, he hasn't solved AT&T growing PR problem -- a problem that is likely to get worse, not better, when MMS arrives.

Below the fold: Seth's latest.

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