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I have a residential PV setup but I don;t understand how to hookup a storage batt to the SolarEdge inverter I have. Anyone can chime in? THe most expensive part is storage.

For (large) home setups I would personally have it done by a company. It might cost more but if anything breaks or is wrong they do the warrenty work etc.   But you will also still be dealing with power mains and connecting to your metered service, house wise. Which I would recommend a professional for just incase, unless you are trained / experienced. 
With that alot of the diy kits and products, they are made to remove most of the guessing and ambiguity.  Sort of how vcr/DVD tv components (dated)came color coded, its not idiot proof but still. As long as you follow order of operations and basic safety when installing you souldnt have too much of a problem.
The battery(s) with the charge controllers and inverters are basic but you can still crosswire them and either short out something or cause a fire.
The self contained units with the inverter and battery are all in one plug and play so those are near zero setup.

Side note. I have been watching alot of his videos lately. He usually seems pretty on it but occasionally he says some things that give me pause. Could just be my personal opinions.

I'm not an expert but,
Lots of places to check on the web. I'm not recommending anything from of exp or even much interaction with the site.
Manufacturer in video, https://www.renogy.com/solar-kits/
https://www.solarwholesale.com/diy-kits/
https://sunwatts.com/solar-kits/
In the end its basically input device like a panel or wind/water turbine etc to a controller which manages the batteries as storage then from the battery to an inverter which converts the battery dc to device usable AC. There is a small loss when converting dc to ac and overhead for each device but nothing is 100% efficent.
Home systems usually go from, dc from panel to a micro inverter on each panel or a macro inverter for a series of panels to the main line as ac. Then to charge the bat back to dc then back to ac from the bat if you need to draw power. Extra steps so a little less efficent. Plus the bat systems arent 100% either.  Like I said, im not an expert.
I like the price point on this battery.
https://buycheapsolar.com/shop/solar-batteries/new-2022-mini-series-10kwh-bsc-lithium-wall-mount-battery/

As with any relatively new technology, the innovations and standards for renewable energy keep changing.  What works great last year might be a wonderful solution praised in many YT videos might be old tech by today's standards. 

There are many similar systems used for DIY and commercial RVs/campers, with and without gas/natural gas/propane generators.

Once you define your application (how much power in terms of amps and length of time to operate), you can better define what technology is best.  Then you can find the people with the most current info on that technology.  There's too much information for someone to try and learn it while also trying to stay up on the latest advancements.  Even if you want to go the DIY route, you should think about a consultant/contractor to help you design the system.  Making bad choices can be more expensive in the long run.

JMHO.  I love to do my own research into new things, but some areas are evolving too fast to know what's available, affordable and also legal (up to code).