So from my knowledge (and actual experience) Vegas 13 has one option for exporting 4k videos. My phone has a 4k camera, and recently I built a beefy computer and decided to edit some 4k footage.
The final product was exactly 2 minutes long, and (not kidding here) exactly 4GB. It was exported to NTFS formatted drive.
The video played fine on MPC-HC video player, and looked great! But why is the file size so huge?! Does Vegas 14 improve on this or is there a plugin for 13 to make it easier?