Panasonic release a new firmware, version 1.2 for the GH1 camera, than hours after that took it off the website and then uploaded a new one. This first firmware allowed you to use 3rd party batteries like the one I bought. Take a look at the video and try the new firmware.

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This is the link to the firmware: http://www.sendspace.com/file/iokwiu
This is the link to a page discussing the firmware: http://forums.dpreview.com/forums/readflat.asp?forum=1041&thread=33069762&page=4
This is the link to the chinese battery @ DealExtreme: http://www.dealextreme.com/details.dx/sku.27951

DISCLAIMER: I DO NOT TAKE RESPONSABILITY FOR YOUR FIRMWARE UPGRADES! DO IT AT YOUR OWN RISK!