Is the screaming limited to one border of Mo'av?
Radak: It is around the entire border of Mo'av, including cities on or near the border. Malbim - the Navi already described the screaming within Mo'av. It will be also on the borders, when they leave their land and the enemy's sword catches them.
What are "Eglayim" and "Be'er Elim"?
Rashi: They are places on Mo'av's border.
Malbim: They are outside of Mo'av's border; the screaming will reach to there, for the enemy continued attacking them after they fled from Mo'av's border.
What is the wailing?
Rashi: It is of Mo'av.
What does the verse teach about "Be'er Elim"?
Rashi: It is as if it says ul'Ve'er Elim" (the screaming will reach until there).
Malbim: It is as if it says Ad Be'er Elim" (the screaming will reach until there, even though it is further from Mo'av than Eglayim).
