Let p = x^2+x

The original expression is converted to

(x^2+x)(x^2+x-1)-2

=p(p-1)-2

=p^2-p-2

=(p-2)(p+1)

Substitute p and continue factoring

(x^2+x-2)(x^2+x+1)

=(x+2)(x-1)(x^2+x+1)