Lithium Polymer Etiquette: a Comprehensive Guide to Working With LiPo: In this Instructable I will be going over the basics of proper charging, discharging, handling, usage, storage, and care of lithium polymer batteries so you can use them safely and effectively in your future projects. Now...
That said, was able to locate the manual (attached to this thread) for the Hawkeye Firefly 4K Split Camera. This unit is actually able to take in a range of input voltages (7-22V; 2S-6S battery).
The camera comes with a power/video cable with pin 1 acting as the positive (+) terminal and pin 2 as ground on a JST style connector. Opposite end is raw ended.
Here's a sampling of 2S LiPo batteries from the same site I believe you acquired the camera from.
If you want to buy cheap 2s lipo battery, choose 2s lipo battery from banggood.com. It endeavors to provide the products that you want, offering the best bang for your buck. Whatever 2s lipo battery styles you want, can be easily bought here.
Information is above. Up to you to decide how to put it together and balance your design to how you want it. Good luck!
I contacted the company. Good news is that Firefly Split cam also supports 5V so we can finally use OTG and can use this 4k cam. I will update you guys as soon as I get hold of the camera. Its still not reached.