I've seen videos of a couple credible doctors who say they've witnessed the phenomenon. 

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Could you post a link? I've heard doctors discussing this, but I've not seen any videos of doctors claiming to have observed this phenomenon with their own eyes. 
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Another theory is that a percentage of the jabs are actually saline so that they could hide the deaths, which would be way too high to ignore if everyone got a real jab.  So I'm on the fence about the magnetization phenomenon.

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I've been thinking the same thing. Depending on what their real goal is, killing half the human race may not be what they want. Maybe they have a target number of deaths they want, that they are controlling with a placebo, as you say.
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I've also been wondering about another thing recently. There are two types of vaccines being used, the mRNA and the traditional-style vaccine such as Johnson and Johnson. Now, most of the evidence that these drugs are harmful has to do with mRNA vaccines, such as the animal experiments using that technology in which the drug killed most of the animals outright. I haven't heard nearly as much discussion about the other drugs causing problems.
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But the weird thing is that the people running this scam seem to be just as satisfied regardless of which type of drug you get, as long as you get one of them. Your vax passport works just as well whether it says you got an mRNA vexation (I'm going to start calling it that now) as whether it was a traditional drug. This seems to militate against the theory that the purpose here is to kill people with mRNA injections. If that were the case, why would they have approved the other type at all?
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I can only think of two explanations for this discrepancy:
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1. We're barking up the wrong tree with the theory that the purpose of the vexations is to kill people, and that it is something else entirely, or
2. that the traditional-style vexations are the control group. By this I mean that the goal is not to kill every possible person, but to kill a certain percentage, say half or so, and the only real way to do that is by releasing four different drugs, two of which are poisonous and two of which are somewhat benign. They started a campaign of terror to convince everyone to inject themselves with these drugs, and that was the only way to get so many people to suddenly inject some sort of foreign substance into their bodies, but they didn't want to kill everyone, so they didn't give everyone poison.

It may be true that magnets sticking is disinfo.
On the other hand, we don't want to throw our the baby with the bathwater.
The OP cites research like this:

Methods Mol Biol.
Superparamagnetic nanoparticle delivery of DNA ναccιnє
Fatin Nawwab Al-Deen ¹ , Cordelia Selomulya, Charles Ma, Ross L Coppel
Affiliations

• PMID: 24715289
• DOI: 10.1007/978-1-4939-0410-5_12

Abstract
The efficiency of delivery of DNA ναccιnєs is often relatively low compared to protein ναccιnєs. The use of superparamagnetic iron oxide nanoparticles (SPIONs) to deliver genes via magnetofection shows promise in improving the efficiency of gene delivery both in vitro and in vivo. In particular, the duration for gene transfection especially for in vitro application can be significantly reduced by magnetofection compared to the time required to achieve high gene transfection with standard protocols. SPIONs that have been rendered stable in physiological conditions can be used as both therapeutic and diagnostic agents due to their unique magnetic characteristics.

https://pubmed.ncbi.nlm.nih.gov/24715289/

I tried it with two people who got ναccιnαted, one with pfιzєr, the other with mσdernα.  The magnets I used are very strong, they can withstand wind against the camo tarp I attach to my truck.  Not the slightest force was noted with either person.  Not the jabbed arm, not the other arm, only a metal belt buckle.  I’m not getting this shot, but I think this is nonsense.  If everyone is magnetized, wouldn’t they have the urge to face and travel to the north?  Now, that would be of interest!

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Thank you! Yes, as I suspected, it's probably a hoax. There isn't enough metal in there anyway to hold the weight of most magnets.