I don't know what 4-step process you are supposed to use.... And the other tutor just shows the factorization of the original quartic equation as the product of two quadratics.
So here is a process you CAN use to do that factorization.
Because of the signs, and because of the leading coefficient and constant term both being 1, the factorization will be of the form
Expand that and compare to the given quartic equation.
This gives two equations in m and n:
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Algebra -- or, better yet, a little playing with numbers -- will find m and n are (in either order) 30 and 67.