Radak: I spoke to you about the nations that do evil to Yisrael ? they will bear their sin. Now speak to your nation ? due to their sin, the nations ruled over them!

Radak: This is like Yirmeyah said "Rega Adaber Al Goy v'Al Mamlachah" (18:7). This informs that He oversees people and bestows good to good people, and evil to Resha'im. Even though Hashgachah is great in Yisrael, there is a little in other nations ? "Rak Eschem Yadati mi'Kol Mishpechos ha'Adamah Al Ken Efkod Aleichem Es Kol Avonoseichem" (Amos 3:2).

Malbim: There are two kinds of lookouts. (a) He is stationed to see if enemies are coming to the city. (b) After the enemy came, they appoint a lookout to look at the enemy camp and warn the nation to guard themselves from the side from which they will wage war, and cast arrows and catapult rocks to the city. There are three differences between them. (a) They station many lookouts in all directions to see if enemies are coming. After they came, one lookout suffices to eye the camp. (b) Commoners suffice to see if enemies are coming. After they came, the lookout must be a general who understands war strategy and can warn the nation where it is dangerous. (c) The king or the head general appoints the first lookout, so if they see enemies coming, he will tell the army to go out to fight. The nation appoints the latter lookout, so if he sees that the enemy will conquer the city, he informs the nation to hurry to [flee, and] save themselves. The verse teaches that if the enemy already came, they take just one; refer to 33:2:3:2.

Radak: This is like "umi'Ktze Echav Lakach" (Bereishis 47:2).

Malbim: He is from the Katzinim (officers) who are at the head of the nation. "Am ha'Aretz" appoint him (refer to 33:2:2:2).

Rashi: It is a lookout.