No. I really suggest you go and read the Wiki article I linked earlier and this time at least
try for comprehension.
Simply put, a noise gate works in this way:
The input signal is applied to the input of a voltage-controlled amplifier (an amplifier whose gain can be set by a DC control voltage applied to a control input port; there are various ways to implement this, but the end result is essentially the same). The input signal is also applied to the input of a level deteector (a circuit which produces a DC output voltage proportional to the magnitude of the input signal. Most noise gates use peak-sensing detection, but on some, e.g. the expander/gate function of the dynamics section on an SSL 9000 series console channel module offers a choice between peak and true RMS level detectors).
The output of the level detector is applied to one input of a comparator and a DC voltage set by the THRESHOLD control is applied to the other comparator input. A comparator is a circuit which provides a yes/no binary answer to the question "is X>Y?". In this case, if the output of the level detector is greater than the reference voltage set by the THRESHOLD control (meaning that the input signal level is higher than the desired gating threshold), the comparator output will switch to the TRUE state.
The on/off output from the comparator is routed through circuits to set the attack time (the time it takes the gain of the gate's signal path to rise to its final value after the input signal exceeds the gating threshold), the hold time (the amount of time that elapses between the input signal level dropping below the turn-off threshold and when the gain of the signal path actually starts to decrease) and the release time ( the time it takes for the signal path gain to decrease from its "gate open" value to its final "gate closed" value).
The result of these shenanigans is a control voltage which is applied to the VCA control port. If the input signal level is greater than the gating threshold the VCA gain will be set to its "open" value (usually unity gain). When the input signal level drops below the gating threshold, the VCA gain will, after the "hold" period if one is set, drop to a minimum value which is usually se with a "RANGE" control at a rate set by the RELEASE control.
So, if you are shooting a video and for some reason have a gate in your audio signal path, what will happen is that if the background sound level is high enough to open the gate (which it would have to be to get your voices, etc. on tape), the
addition of an explosion sound to the mix would simply help to keep the gate open. This would have no effect at all on whether the explosion- or anything else- made it to tape.
You can download the user manual for the Drawmer DS-201 2-channel noise gate (an item which is
de rigeur for any studio worthy of the name)
here. While the schematic is not included, there is a block diagram and explanation which might be useful in understanding how gates function. Or you could find the schematic for the DOD FX-30 gate
here. This is a cheap-and-cheerful gate pedal for electric guitarists; it uses a JFET as a voltage-controlled resistor/switch for audio gain control instead of the Blackmer VCA ICs commonly found in studio-quality gear, but if you can read a schematic you'll see that the elements I outlined above are all present, and perhaps even see how it works.
Now before anyone who might be wandering the electronic forest like a lost child decides that it's comp/limiters to blame for the absence of recorded blasts in videos they might want to read
this post, in which I investigate the effects of a limiter on combinations of loud sounds on a softer background.
