Ehh, I would say that you take any sort of "Minimum System Requirements" with a grain of salt.
A mechanical keyboard should be just fine, as long as you can connect it to your PC, same goes with the monitor
As to whether a gaming PC can handle video editing, it depends on the parts, in the case of video editing the CPU matters more than the GPU, considering that not all programs support all GPUs when it comes to a GPU's ability to encode video.