Using today's technology:
CPU - Snapdragon 808
RAM - 4gb
Memory - I don't care as long as it's MicroSD expandable
Screen - 4.5" 1080p, I like a smaller formfactor, have a plastic screen with a tempered glass screen protector
Body - External soft touch plastic like the Nexus 5 packing an internal metal frame for support, and like huilun2 earlier it should be IP68. Maybe a pseudo-leather vinyl wrap could feel better than soft touch?
Battery - 4000mah (Doesn't need to be removable, I never interchanged mine in the first place it just needs to be serviceable)
Camera - Something that's fast and can take lowlight shots like the Nexus 6/5X camera
Sound - Like in the video, Boomsound speakers, a good internal DAC would be a nice addition.
Misc: USB-C, some sort of fast charging variant, NFC, wireless charging, a fast memory controller, 4G, a good camera flash to use as an emergency torch
As for software I'd use rooted Marshmallow with Greenify or something like that to preserve battery life.
I'm not sure if this is even possible given how lots of technology reacts with high powered magnets but an electromagnet which you can switch on and off through the OS would be pretty nifty, depending on how loose your pockets are it could keep all your keys together and you could just place it on a magnetic wireless charging base on a wall or something.