A person devoted to arguing or bickering about defining genres of music, particularly electronic music, on youtube videos. Usually they know fuck all about music and have no interest in admitting they are a fool and know nothing about what genre is what, but they like to tell you what is what.
"They know what is what but they don't know what is what, they just strut, what the fuck"
Genrenista #1: "OMG that's totally Dubstep that transitions into Drum & Bass"
Genrenista #2: "No this is totally Electro House"
Genrenista #1: " Go kill yourself, this is totally Dubstep, like omg"
Genrenista #3: "Like WTF this is totally skrillex, isn't he his own genre?"
Genrenista #4: "Um, this is post-folk hipster nu-disco, like duh"