1)
What will Madai do to Bavel?
1.
Rashi: Daryavesh ha'Midi killed Belshatzar - "Bei Beliliyah Ketil Belshatzar", "v'Daryavesh Mada'ah Kabel Malchusa" (Daniel 5:30, 6:1).
2)
Why do they not desire gold?
1.
Rashi: They want only to kill and avenge the evil that Bavel's kings did to all the nations. Radak - they will not accept redemption - "Okir Enosh mi'Paz" (12). Malbim - this discusses what they will do to the natives of Bavel. Against the foreigners, they came only for money - to plunder their houses 1 . They denied the importance of silver. No one can deny the importance of gold; even so, they abandoned it and went only to destroy.