I have a collection of about 1800 (yes, eighteen hundred) video discourses in the form of VIDEO_TS folders that fit just onto two 4 TB hard drives. Because I want to have these videos (in a separate library) in iTunes I have converted them with Handbrake into mp4 files. I was hoping that they would fit converted onto one single 4 TB hard drive. However, they don't. I am about 200 GB short. Is there a way to compress all or some of these mp4 files so that I fit them all - together with the iTunes library file - onto one 4 TB hard drive?