the video claims it "Steam Ship" and not "Screw steamer". But later claims TSS is "triple screw steamship". So I'd be hesitant to trust the rest of the video's content.

The first steam ships were paddle steamers, wiki even says SS can just be a generic term for steam ship.

It's not unusual for acronyms to have multiple meanings, the S in HMS can mean submarine, as submarines aren't ships.