Disclaimer: I'm sure this is snake oil, but I'll try to give a comment as neutral as possible. But don't take it as endorsement. And if you see some hidden bias, you are right.

ClO2 is very similar to bleach/chlorine, but weaker. Chlorine can be used as a good disinfectant outside the body, an you can take a small amount. (In many places tap water contains a small amount, or you can add a few drops of bleach to avoid some illness. Only one or two drops per liter.) I guess ClO2 is also useful as a disinfectant outside the body, but I really doubt it is useful inside the body.

The problem is that the ClO2 is an oxidant, but it will react indiscriminately against the first thing it finds. (Exactly like bleach/chlorine.) It is fine to clean a table, or some equipment, because some materials don't react too much and it will cause burns the virus, bacteria, and even a bug or another unlucky thing that is there.

In the body it will react with whatever it encounters, like sugar or normal proteins, antioxidants or whatever it finds first. If the idea is that you drink ClO2, it goes to the guts, then to the blood, and then to the lungs, then the chance that the ClO2 will survive all that trip and then reach the virus is tiny.

The antivirals drugs are drugs that don't react with everything. The virus are very small and you are big, so if they are not specific they will react with you instead of the virus. Some of the antiviral drugs bind with a part of the virus. Some bind with the part of your body where the virus attach. Some are slightly broken versions of normal molecules, that are ignored by your body but confuses the virus.

Anyway, hand waving is not enough, the important thing are clinical trials. He claims that he has been proposing this for a few decades and that it is useful to treat similar coronavirus in other animals. Is there any study with a randomized control group published in a journal with peer review about ClO2 as a cure for any illness?

Even for animals, if it works in dogs and cats it may work in humans. There is nothing specific in ClO2 about humans. It is much easy to make a study with rats than with humans, because there are less ethical problems.

Most of the context info in the video is right. But I'm worried that the important details are wrong, very wrong.