Hmm, really hard to see much from that video, but some guessing below. Based on that, I would say that the build focuses on CDR to have high uptime on WoTB. Stun on hit for survivability and parthan proc.
Cube ring: Probably skull grasp, since he has CoE and Zodiac equipped
Cube armor: Hexing pants or Mantle of Channeling, probably mantle for the defensive buff
Cube weapon: Furnace is most likely
Belt is Cassius
15% life on chest
12% something on his gloves, must be AD, secondary rerolled to stun on hit rerolled
He has parthans, probably activated by gloves/weapons, and has rerolled a secondary stat - likely to be melee damage reduction
On his CoE he has AD, +dmg (?) and CHC
Other Ring is perfect zodiac with RCR rerolled to socket
He doesn't have WW skill dmg on helm, but he does have it on boots
Amulet is a nice 19% phys/10%/100% (he must have a lot of time on his hands!)
Wpn 1 has AD, STR, VIT, and stun on hit rerolled
Wpn 2 has CDR, AD (rerolled), STR and stun on hit
LMB: He doesn't have warcry, but instead using Threatening Shout. Perhaps with falter?
RMB: WW, presumably with blood funnel?
S1: Ignore pain, probably with iron hide. With cassius, CDR gear and zodiac, this is probably up permanently
S2: Overpower, probably with killing spree?
S3: WoTB - guess with insanity or striding giant?
S4: Battle Rage - bloodshed or into the fray?
Gems: Taeguk, Stricken for the first two. The last one appears to be moratorium (14:57)
1: Rampage buff shows up on video, so thats no 1, other than that, we only visible buffs are taeguk and CoE, so whatever else skills he chose, they don't have a buff icon
2/3/4: I'd guess wpn master (since he is always full fury), unforgiven (since he does not degen fury in town) and beserker rage (since he's always full fury that makes sense)
Warning: it's much weaker than Raekor or MOTE at the moment.
As you can see in the video, he got a GG rift and mobs (Floor 1 Spire with fatties, zombies, summoners, and thralls, Floor 2 and with same mobs on Crater, and decent floor 3 Realmwalker), a very good Conduit pylon. He made 80%+ of his progress on Floor 1 and actually lost time on Floors 2, and 3 due to some bad mob affixes. RG was Crusader King, an easy win (though not the ideal RG). He would improve his damage by swapping Taeguk for Trapped and using Diamonds in gear. He's also got 100+ augments on everything (23k+ main stat), so gear and gems aren't a problem for him.
Well, it sort of is dead and weak. It's not competative with MOTE or Reakor at all in terms of how many hours you'll need to farm gear to get to grift XX, but once you have a good set, it's useful for speed rifting