Another way to solve the problem in this lecture

Dear 365datascience team,

Somehow I came across a following solution(exactly the same) to the question taught in this lecture,

but not sure about whether it's a self-join or not? 

Besides, since there are so many solutions to this question, I wonder any benefits to use self-join? Thanks!

SELECT
    e1.*
FROM
    Employees.emp_manager AS e1
    INNER JOIN
        Employees.emp_manager AS e2
        ON
            e1.emp_no = e2.emp_no
WHERE
    e1.emp_no
        IN    (
            SELECT
                e2.manager_no
            FROM
                Employees.emp_manager AS e2
        )
;