He has not posted any part number for the component he has, so are you sure that you know the pinout?

In this case, he claims that one connector is VCC and one is GND. This means that it is not a crystal with two ground pins, but it a complete oscillator module that contains electronics to produce a digital output signal. These modules can be had with 3.3V or 5V digital output for direct connection to digital inputs of a processor or to discrete logic.

A crystal on the other hand requires that you feed a signal on one side of the crystal, to drive it, and pick up an analog signal from the other side of the crystal. One crystal pin of the processor is driving the crystal, and one is detecting the oscillation. Some processors - not all - can accept both a crystal or a direct digital signal on the input, so you may even connect a complete temperature-compensated oscillator module to such processors. The datasheet for the specific processor, or application examples, should normally tell if the processor requires both pins to be used for a crystal, or if one can be ignored, and the other used with a digital clock signal.