Thousands of containers arrive in the country every day, and in a short time it is hard to know to whom these containers belong. Until the ships reach port and the required registration is done, they won’t know what fell and what didn’t, and by then days or even weeks may pass before the owner knows that he is the one who suffered the loss. Nowadays, with imports wide open, there are many small businesses that import and sell, and damage like this can cause them financial collapse and large debts. Is there still no issue of theft here? This is not something the sea gave as a gift, but the livelihood of a particular person who still doesn’t know it, which has been thrown into the trash.

This is a very complicated discussion. Morally, the answer is clear, and therefore the halakhic discussion is only to magnify Torah and glorify it.
If “what the sea swept away” is based on despair of recovery—and that is not clear; see Ritva and Shitah Mekubetzet on Bava Metzia 21—then seemingly this is a case of despair without awareness. But perhaps in the case of “what the sea swept away,” even without awareness it is considered despair. The question of whether this case is indeed “what the sea swept away” is also unclear. As long as at the time of the loss it was possible to save it, it seems simply that this is not “what the sea swept away.” It is lost property that you, as someone present there and able to save it, must return to its owners. So to what case was “what the sea swept away” said? To something already in a lost condition, and only afterward a situation arose in which it could be saved and taken from the sea.
All this requires clarification, and the question is not simple.
I just saw a discussion here: https://mercazharav.org.il/2019/07/05/%D7%91%D7%A1%D7%95%D7%92%D7%99%D7%99%D7%AA-%D7%96%D7%95%D7%98%D7%95-%D7%A9%D7%9C-%D7%99%D7%9D-%D7%95%D7%90%D7%91%D7%99%D7%93%D7%94-%D7%A9%D7%9C%D7%90-%D7%9E%D7%93%D7%A2%D7%AA-%D7%9B%D7%90-2/

Is it really so immoral, if in any case the products won’t reach the owners and other people are the ones who will benefit from them—why should we just stand by and watch our neighbors divide up the loot while we get no benefit too? One could add that even if nobody had touched the products, it still isn’t clear whether the owners would have come to save their property, and even if they had come at some stage, until then it isn’t clear whether the products would have remained intact—so at least let others benefit.
From a halakhic standpoint, maybe here this counts as conscious despair, because presumably the owners of the shipment are also following the news and despair of recovering them on the chance that this really is theirs. Or is this not considered despair, because they still hope it’s not theirs?

I really didn’t understand why the Rabbi calls them subhuman. Why wouldn’t the Rabbi have done it himself if it had been near his city?

Personally, I assume it’s obvious there is despair here, because presumably all the containers are sufficiently insured, and no importer is going to start cleaning products from salt water…

What does that have to do with anything? Do you know what kind of insurance he has and what deductible he has to pay? There may be small importers there who will collapse because of this. And what about the insurance company—is it permitted to take from them?!

Halakhically, I already wrote several points. Morally, there is no doubt that this was hideous in a disgraceful way. If they can save it, let them save it for the owners. There is even someone there suing the police because they took from him a whole container that he had dragged away with his boat. People who are absolute scum.