There may be a little of color enhancement going on here, and it may also be a long exposure that's been mirrored over one axis, but, otherwise, this is exactly what it looks like when you burn a fuel droplet in microgravity.
Setting things on fire in the International Space Station sure seems like a terrible idea, but that's the whole point of FLEX. FLEX stands for "Flame Extinguishing Experiment," and it's intended to "assess the effectiveness of fire suppressants in microgravity and quantify the effect of different possible crew exploration atmospheres on fire suppression." In other words, NASA needs to know how stuff burns in spaceships so that the agency can figure out the best way to put fires out.
It may be important research, but it's not like they just gave the astronauts a Zippo and a bunch of volatile chemicals and told them to be careful. The Multi-User Droplet Combustion Apparatus uses robot arms to release tiny droplets of different chemicals one at a time, burning them in a specially sealed chamber while recording data. In the top pic, for example, you're looking at a burning drop of heptane (mostly in yellow) giving off soot as it burns (green) and shooting off little sparks (red). This is what it looks like without all the false-color shenanigans: