Sorry, did I miss something? I didn't see any mention of a national gun registry mentioned in the video. Double checked his website, don't see any mention of registration. Regardless, you are incorrect, universal background checks could be performed without a firearm registry. A good, responsible citizen will check for the background check and even if they didn't write down the name, that doesn't make him useless to officers investigating a case.
How do you enforce ID check requirements for people selling alcohol? You could do the same thing with firearm sales. Of course some people will cheat but if cheaters were a reason to not have a law/regulation then we wouldn't have any at all.
My god, you're dense -- and naive.
They want to put the cart before the horse. Once the law is in place to require private party sale background checks, and the weakness is displayed, then they will come back and add the registry. That part will be more time consuming since there are laws that currently make one illegal -- have to modify or repeal those.
Common sense is lacking with you. If the UBC system is to work, the government must know who owns every single firearm. Otherwise, there's no accountability for any sellers. A gun that changes hands after the initial sell may have zero documentation to record the buyer and seller.
Not everyone gives a flip about generating and signing a bill of sale. The buyer may not even know the seller's real name. Why would he care?
Then you have to factor in the number of people who aren't knowledgable of the law and will skip the background check out of ignorance.
If there's a fee, others will skip it to save money.
If the buyer offers a little above asking price to not run the BG check ("I had a domestic argument 20 years ago with my ex but charges were never filed, so I might have a problem passing..."), how many sellers would be okay with helping someone out who's being denied a right under those circumstances?
"A good, responsible citizen will check for the background check and even if they didn't write down the name, that doesn't make him useless to officers investigating a case." So, you basically think the honor system for firearm felonies will work? With all the gun laws on the books, that's your answer?

Obviously the government doesn't share your optimism.
And I never said the gun owners would be useless in an investigation. What I said is they won't provide enough details to qualify as evidence. A seller who doesn't run a background check before a sale is knowingly breaking the law. He's going to use a fake name, meet where he's not near his home, use a phone or email that can't be associated with him, and not have any records of having owned the gun himself. The buyer will be unwilling to cooperate because he'd be admitting he knowingly bought the gun without a background check (skipping it benefits him more than the seller). Someone looking at a felony charge might be persuaded to identify the seller, but (1) can he?, and (2) would his identification hold up without any corroborating evidence? "Yeah, that's the dude." Dude: "He's mistaken." Not much to go on when the buyer has every incentive to lie in exchange for a charge reduction.
As for checking IDs -- alcohol sellers (liquor stores, bars, Costco, etc.) are licensed by the state. If they fail to do the minimum due diligence to make sure buyers are of legal age, they can not only lose that license, but they can be criminally charged as well. There are cameras that can prove whether the store requested ID and can prove that the buyer purchased from that store. There are register receipts that track inventory and prove what was sold at that time. None of this exists with a private gun sale.
Not to mention that there is no law currently that requires you to check a gun buyer's ID, even though you can't knowingly sell a gun to a resident of another state without using an FFL, nor can you sell to someone who is under age. A quick check of a drivers license can verify those requirements are met, but it's not punishable if you don't check an ID. And, just like a liquor store or bar, fake IDs can be used to bypass those restrictions.
Your comparison is lame. Unless private firearm sellers are required to apply and pay for a license to sell their guns, there's no similarity with checking ID for alcohol sales.