Wall Mounting a tv, how much can my wall take?
A stud can hold much more weight than a 20 lb TV.

However, since your mount extends, that 20 lbs will actually add a lot more force to the mounting location.

You will still be fine as long as you are mounting directly to a wall stud. You should be certain that you are screwing it to the center of the stud.

Also, follow the installation instructions with the mount. With such a small mounting footprint, I think it is more important that you get everything correct.