I compiled three easy methods to make a welt pocket. The first one is shown in the video. The next two are so simple I don't need a video to explain it.
.
1) "Cut and clone" method
Basically, clone the pocket outline. Sew the upper clone 'flush' with the bodice fabric except the top part, which remain open.

.
2) "Cut and sew" method
Just "cut and sew" the pocket outline. For more effect, increase and vary the 3D seamline thickness.

.
3) "Topstitch" method
No need to cut anything or create a new pattern. Just apply textured topstitch (not obj). Set the offset to zero and enable 3D. Increase and vary the 3D thickness.

.
.
As you can see, there is not much visual difference among the three. I will only use the first method when I want the pocket to open slightly, such as the "side slip pocket" on a bomber jacket.
Another obvious method that I do not recommend (but I often use), is to sew the pocket piece to the outline without cutting anything. The problem with this is that the pocket does not "flush" with the fabric. It looks more like a sticker than a pocket. But is some design, this is intentional. This is also the method to make a "patch pocket".