Agonized about posting this but, in the interests of jointers everywhere, I feel I must.
This video should have been called "How to NOT set up a jointer".
You started off checking your cutter head using the outfeed table as a reference..... and then you moved/shimmed the outfeed table.
Just think about that for a moment.

One of your tables might have had a slight dip in it but that, while not ideal, is not the cause of your troubles.
It does take time, trial and error, to get your both tables coplanar.
Use your outfeed table as a reference and then set everything else to be coplaner to that.
99 x out of 100, it should only be necessary to use shims on your infeed table.

Lastly, (I might have missed it) you never mentioned or checked your blades.
YT  is full of videos showing how to properly set the height of your blades with the aid of magnets and a dial indicator if you dont want buy the knife setting jig.

There are thousands of people around the world using jointers older and "worse" than yours that work flawlessly.
Spend a bit of time on YT and you'll find lots of videos showing how to PROPERLY set your machine up.
You will not regret it.

Just got a “good deal” on one of these jointers. On the way home someone cut the straps when we pulled off for lunch. Came back to the truck with parts I’ve never seen laying on the floor of the trailer. The business owner just so happened to not have any footage from the cameras that pointed directly at my vehicle.  Thanks for the setup video, I’ll be doing the same this weekend

Hey man, I applaud your valiant effort. I have a Jet 6 inch, 4 years old. Worked great . Last year I had to remove the tables to replace busted ball crank on infeed table. Put it all back together and jointer has never been the same. I mill up some boards and all is good. Start a new project and boards come out whack! I didn't touch anything! My machine is demented.

Hello Lindsey, I found your video because I bought the same used jointer and Im doing maintence, my engine drifts when I turn on the jointer & Im thinking its the belt. I can find any info what belt size. And thats because Im here asking if you could help me with the belt size you have. Regards

Have you thought about covering the fence with a piece of MDF (with shims) to make it flat?  Sure you will lose .5 to .75 inches but it'd totally be worth it.

Thank you for this, most practical setup I’ve seen for a dovetail, cheers from Australia 👍🖖

.0015 is fifteen ten thousandths, or one and half thousandths. First place to the right of decimal is tenths, second  place is hundredths, third place is thousandths and the fourth place is ten thousandths. Called a tenth and not to be confused with a tenth of an inch.

Not bad for using common sense and simple logic . Dovetail way jointer aren’t really meant to be adjusted. They get messed up from people lifting the machine at the end of the tables.
Your process was about halfway right.
Too me it doesn’t really look Ike you need a jointer right now. Beginning stage of a woodshop?

Take back fence and take it to an engineering place to have it skimmed flat .. shouldn't be to expensive to do ..they do it on car cylinder heads all the time .

Your fence is warped. My old powermatic manual gives instructions on how to correct a warped fence. Check the manual for your delta and see if it gives instructions. Or do an internet search.

Have you tried splitting the difference between the infeed and outfeed table, getting it close enough?  You could square it up on the table saw by just ripping both sides without any special method or jig.  Since the edge your creating is flat just angled you shouldn't need stumpy nubs method.  

If you are happy enough with the tables being co-planar then it seems like your fence has a twist.  You could just have the fence ground flat at a machine shop, not sure what that would cost.

As far as a parallelogram jointer, that would make getting the tables co-planar easier in the sense you wouldn't have to shim, but if the fence had a twist you would have the same problem getting square sides.

I used to have one of those. I could never get it to be co-planar and adjustments were janky as hell. Do not buy one.