So, I purchased an aftermarket battery, I decided to run the camera through all it's functions to make sure. It worked fine for photos and seemed to capture video just as well. However it would not play any of the video back I kept getting "Cannot play video". I tried switching the camera off and on to no avail. Naturally this concerned me, so I switched back to the OEM battery which then played the videos just fine. The brand was power2000 and it was a 7.4v 1500mAh battery, I chalked it up to a gremlin that needed 7.4 volts to wake up, and am returning the battery. Think I'm going to look for a 7.2v next time

Has anyone else had similar problems with after market 7.4v batteries?

no issues at all. I bought 2 7.4V 1200mAh no brand batteries on ebay and so far no problems.

Well, I was just reading another thread and it seems that these cameras don't like Patriot memory. I currently have a 8gb patriot class 10 card, so I'll have to buy another brand and re check the battery to be sure it's not a combination of both causing this.

I've got three 16gb class 6 cards that vie been using and they've worked fine. I have, however, only used the official batteries.

I have 3 7.4 1200mah after markets from ebay. No problems of any kind noted, tho one seems to recharge longer then the others.

Well this one stumped me, I just bought a new SDHC card and I haven't seen the error again. I've decided to exchange the battery also, just to make sure. I'll try out a 7.2 aftermarket battery next and see how it goes.

Definitely interesting that a battery would cause a problem like that only during PLAYBACK.
I can hear Howie Mandel: "Doctor said turn your head and cough...okay. But all I want to know is...where's the connection???"
I've got 2 OEM batts and a 32GB Patriot. No problems here.

My money's on the patriot card being the issue because I had problems with two Patriot class 10 16GB cards and had to return them both. It is possible that there is some strange combination of battery and card, that would be good information to send off to Patriot..