Regarding the miniature camera/transmitter which Wilf discussed:
This camera/transmitter uses 3.2 to 5.5 volt power, which gives lots of options for batteries.
This particular one, like other similar ones, may be intended to run from a small capacity single cell battery. However, that battery is unlikely to operate the system for more than, say, 5 minutes and is therefore a poor way to power it .
We make a cable which will plug into the camera's connector and then into the balance port of a LiPo. That way, one can be in operation on any plane by simply having a small patch of hook-side Velcro stuck wherever you want the camera to mount and having access to a battery - we normally use the LiPo that powers the aircraft.
In the case of using your LiPo, the cable connects to any 2 adjacent wires on the balance plug. As the cells are connected in series, the voltage will be that of 1 cell, right in the required range. Note: you MUST get the polarity correct!
The very small current draw will not unbalance the LiPo.
So, if you want to try this out on your own aircraft, just ask one of us. We even supply the Velcro! And we have several varieties of the receiving and viewing equipment.