I couldn't glean much information from the clip.
Lots of disturbances develop enough energy to cause lights viz, St. ELmo's fire, glowing on helicopter blade tips in some sircumstances, electrical sparks.
Some slo-moes of bullet impacts even show a small fast flash on contact with material not noted for sparking. I remember slight flashes when ordinary rocks were hit with my .243 in dusk conditions.
Don't forget that most of the time you're observing things at a macro level, not at the micro level. Your 3000 fs bullet may be generating much more high speed particles on contact. Since velocity is temperature, high temperature means light is generated.
