Watch your clips without leaving the library.

You're sitting on a folder of clips you shot last week. You want to watch one, check if it's good, maybe trim the fat off the end. Before, you had to open it in a separate player window, close that, go back to your folder, find it again. Now you click play right there in your folder and the video starts playing in the same window. You watch, you decide, you move on.

This sounds small but it saves you the back-and-forth. Especially if you're going through a bunch of takes and only a few are keepers. You stay in one place, you work faster.