Highlights for me is that he has a lot of conditioning. Multiple bikes for intervals and steady state efforts, rower, ski erg, treadmill and the "spinny thing." The spinny thing is supposed to simulate speed bag movements and is a device used by boxers and MMA athletes for shoulder, upper arm, forearm and wrist endurance. I feel like a set of battle ropes would get you all the way there, are cheaper and more versatile.
He also advocates competition bumpers and change plates yet does not promote high end bars. The 300# competition bumper set plus 35# change plate set will set you back $1140 + $190 but will certainly last a lifetime and have a good feel and is all you will ever need. The Ohio Bar by comparison is a budget friendly $295. While he claims he only advocates a 300# set, there is easily 1200# in his gym.
There is also a lot of strongman stuff including dead balls, sandbags, log, and grip training implements. Famously in the past, he also bought a pig (although it is not in his Tennessee home gym).
I certainly agree that a timer is clutch. His other accessories include Crossover Symmetry, bands, jump ropes, Spud Inc. accessories, abmats, ab wheel, furniture sliders, etc. I have certainly accumulated a ton of accessories as well. It seems like I just find something interesting and want to have it.
Mat is a strong advocate of a GHD and Reverse Hyper but freely admits the footprint is large. I bought and sold a GHD and rarely regret it. However, at some point in the distant future, I would like to come across a Sorinex Frankenhyper ($3300) as I like throwing in GHD sit-ups and have used a Reverse Hyper for rehab and prehab. For bodybuilding, I would like to get a Sorinex Lat Pull Down Low Row ($3000) as those movements are much more comfortable with selectorized weights.
He also mentions artwork in passing. He goes as far as taking stuff off the walls and setting it right in front of the cardio equipment to bring to mind some inspiration and focus.
Additionally, he describes the following at length:
Lifting Platform (8x8) - want
Dumbbells (5-100# + 125#) - have some
Kettlebells (big range) - have some
Plyobox - have
Pegboard - not sure if I want
Rig with pull-up bar - have a good solution
Rings - have
Climbing rope - have
Pulley System - not interested
Curl Bar - have with standard plates
Axle Bar - have
Elephant Bar - have used, but not often
Weighted Vest - have
Med Balls - have
Parallettes - have
Flat Bench - have
Iron Neck - never used
One of the few oversights is flooring which he does not discuss at all, but I believe is vital for a training experience.
Finally, one concession he makes is that he considered that (2) people may train together in his home gym, but that has never happened.
Mat's recommended Gym
Rogue Echo Bike or Concept 2 Bike Erg - $795 or $990
300# competition plates and change plates - $1330
Rogue Ohio Bar - $295
Rogue S-2 Squat Stand 2.0 - $425
Rogue 150# Sandbag - $90
Spud Inc Econo Pulley System - $110
Rogue Utility Bench 2.0 - $180
Rogue Home Timer - $150
Total $3375 or $3570 depending on bike. Shipping would be extra, but you are getting close to $5K ships free.
I have a version of all implements listed except for a pulley system.
Stationary Bike on Travel Trac - $750 for bike + $125 for trainer - $875
490# Mixed Plates - Rep, Rogue, Weider (Crumb, Rubber, Comp, Iron) - $809
Rogue Beater Bar - $80
Rep Folding Rack - $240
Brute Force Sandbag - 50# - $125
Pulley System - NA
Cybex Flat Bench - $25
Rogue Home Timer - $150
Rogue sponsored athletes often do these reviews and I have seen Josh Bridges home gym among others. While they are primarily promotional, they are a lot of fun. I also enjoy the "What's in the Bag" videos.
While certainly a separate video, I feel like athletes often have a full host of recovery gear and supplements.