Most seafood you eat that you didn't catch yourself was frozen. Properly prepared and frozen seafood can taste better than unfrozen. And yes, their unfrozen foods that are going bad get turned into soup, but that is a normal restaurant thing.
I just don't get it. Who can respond positively to the continuous 1/2 second fast-cut edits and obnoxious "hard rock" music of videos like this? It's like everybody involved wants to advance from producing cruise ship documentaries to working for early 1990s MTV or something.
Of course it's not the most in-depth rigorous study of on-board ship operations, but what do you want / where else are you going to get a glimpse inside the ship for a popular audience? It has enough info to be useful I think.
Consumers can buy seafood at the grocery on, say, any given Thursday because they know the delivery truck makes periodic visits. And if they learn that schedule on a Tuesday they can wait it out two days until the phase wraps back around with fresh(ish) lobsters.
The phase reset on a cruise has the intended effect of re-supplying the fresh(ish) lobsters but with the unfortunate side-effect of dropping you off at the shore.
Lobsters are a weird example because they're usually alive in the tank (at grocery stores around here they're the only live animals sold) so I wouldn't think "fresh" would matter much?
It is a mix. Resupply depends on many factors. Remember ships are stopping at different ports - and often different countries every day (except for cross ocean cruises which of course which don't stop). Thus they look into local taxes, availability, and such. Meals are planned which means they know what they need - but also means they can look at what will be available. They have the ability to load at any port. If they can get X cheap at some port they will buy it there. Thus if they can contract a local farmer to supply something cheap in one port they will. If shipping means some non-local food is cheaper in one port than another they will buy at the cheaper one. If labor is cheaper in one port they will try to use more of that labor.
Supply management is important to a cruise line. They are very good at getting the best prices. They take advantage of the ship moving to get the best prices.