just curious why isnt mp4 supported here? it has to be converted to webm. which is some what inconvenient imo. is there a reason for this? i didnt see anything in the forum about this so just asking is all.

e621 does actually serve mp4 files since some inferior platforms do not support webms for whatever reason. Still, in case of a cease and desist notice (or whatever legalese is proper here), mp4s can be safely nuked and primary webm (re)encodes will stay.