Voltage conversion for quadcopter camera
Depending upon the quadcopter controller, there might already be a LDO 3v3 regulator somewhere on the board. It might be good idea to reuse it.

If it doesn't work out, depending upon current draw on 'Yellow' control pin, a fairly large resistor with a parallel 3v3 zener could be used in a prototype/PoC attempt.

I'd probably explore other choices like LDOs before looking at zener option. While it sounds a bit cheaper, the zener keeps draining the battery even when the line is not in use. There are some fairly cheap LDOs available in tiny packages (e.g. http://www.newark.com/torex/xc6206p332mr/ldo-voltage-regulator-fixed-3/dp/18K7646 - may not be useful in this case, though).