Fire breathing in any time is pretty nuts, but in bullet time it's something else entirely.
"Bullet time" refers to the visual effect of having a scene appear to playback at normal speed from the viewer or camera's perspective, but with the subject of the scene slowed way down or even stopped. So, a bullet traveling at 1500 miles per hour (or so) that's being viewed in ultra-slow motion can be danced around by a regular speed camera as if it were a Thanksgiving day parade. Cool.
The effect is achieved in real-space (vs. video game graphics etc.) using multiple cameras—48 DSLRs, in this case. Stuff like this is Director of Photography Mitch Martinez's thing and you can find a few more (along with a making-of video) at his webpage here.