i've actually tried that before, takes all of about five minutes to set up, and mine didnt work quite as well as the ones in the video, but i half assed it
works with any flammable liquid, so far lighter fluid, white spirit and deodorant work best alltough deodorant smells
last summer i made on about the size of a tennis ball from e cloth drenched in white spirit, those things are uber cool, but wear gloves then and throw the to friends and back, its fun !
i even took a headshot for 10euro, just some burned hair and 10 euro richer
i have done it and it works. It's scary though at first. just holding fire takes some getting used to. but definitley fun and easy if your bored. same thing with flaming tennis balls