What is the meaning of "Yotzerei Fesel Kulam Tohu"?
Radak: The craftsmen who make and form the idol are Tohu (nothingness), for their acts are Tohu.
Malbim: Those who denied Hashem's Hashgachah served stars and idols. There were three castes. The lowest attributed divinity and power to these forms. This is folly - the smith put this 'divine' form on them! Also refer to 44:9:2:2,
Why does it say "va'Chamudeihem Lo Yo'ilu"?
Radak: The idols that they cherish, they are useless - why do they cherish them?
Malbim: A second caste of idolaters thought that the idols are a means to draw influence from a star that loves that form. The verse says that the stars do not love the forms, so they will not get any benefit from them.
What are witnesses?
Rashi: The idols are witnesses of the shame of their worshippers. We see that the idols do not see or know, and they worship them!
Radak #1: If they will say 'we do not know that they do not help', the idols are witnesses about themselves, that they do not help. They do not see or know. Since They do not see, hear 1 or know, how can they help others?!
Radak #2: The idols testify about themselves, that they have no power. If you will burn them, they cannot save themselves; all the more so [they cannot save] others!
Malbim: Yisrael are witnesses of Hashem's Hashgachah - the idol worshippers are witnesses about their idols, that they do not see to supervise over them; also "they do not know" anything.
Perhaps Radak added 'hear' based on Tehilim 115:6. (PF)
Why does it say "Lema'an Yevoshu"?
Rashi: Those who serve them will be ashamed.
Radak: Mention this, so they will be ashamed to serve them
