I don't like this creator (Bellular News), so won't watch the video. Instead I copy description and timestamps over:

How many games have been sitting on your Steam wishlist for years? New releases are struggling to turn that interest into sales, and Valve has changed how wishlists work to help. With more players waiting for discounts, developers need their games to keep selling long after launch.

00:00 Steam's Wishlist Problem
00:34 Why New Games Are Struggling
01:23 Steam's Wishlist Changes
02:54 Do Wishlists Sell Games?
07:24 Waiting for a Sale
09:15 Surviving After Launch

Ah, I see its about the new added wishlist feature. You can now add custom tags to group your wishlist items. That was indeed a feature some people requested and I would have benefited from this in the past too. It helps reminding you why you added the game to the wishlist. Maybe its about something else, didn't watch.

Edit: In case you can watch videos on other platforms, and just don't want to or can't use YouTube directly, there is an alternative frontend: https://inv.nadeko.net/watch?v=9HPNlYot6uY