Extraposed subject?

“The surgeon, Dr. Somerton, was a fast, sporting young chap, and the other young officers would meet in his rooms of an evening and play cards. The surgery, where I used to make up my drugs, was next to his sitting-room, with a small window between us. Often, if I felt lonesome, I used to turn out the lamp in the surgery, and then, standing there, I could hear their talk and watch their play. I am fond of a hand at cards myself, and it was almost as good as having one to watch the others.”

The Sign of the Four, novel

Hi. Does the dummy “it” in red refer to “to watch the others”, which is an extraposed subject of “was almost as good as having one”?
Thank you.