I have never actually used a fire piston myself, but I understand the principle and I know that many people use them for starting fires in the wilderness.
If you don’t know what a fire piston is – a fire piston, or a “slam rod fire starter” as it’s sometimes known, is a small tube/piston that uses rapid compression of air to create heat. When the compression is high enough, the heat generated in the air chamber ignites the tinder material, which is then used to start the fire. As in the video, it would seem to me that charcloth is the best type of tinder to use with this method of fire starting. See: How To Make Charcloth (For fire starting)
If you watch the video you’ll see how the fire works, whilst also seeing how to build one yourself.