If I select Watch for a posting it in highlighted in red.
But else does it do, if anything?
This feature allows you to mark articles as important or to read later or similar.
So basically, it doesn't do anything else… It could, perhaps, set a flag whereby the user could bring up Watched items even when Hide Read was operating.
Actually, it doesn't do anything special. You can use the TAG function even better because you can filter for tagged messages.