What is the meaning of "ha'Lo Yad'u"?
Rashi: They knew their end, what happened to them.
Radak: This is said in astonishment. How could sinners and afflicters of Yisrael be so foolish not to know that Hashem sees and knows their deeds?!
Malbim: Refer to 14:5:2:3.
Who are "Ochlei Ami"?
Rashi: It is Nebuchadnetzar's seed.
Rashi citing Chazal: It is those who steal from Yisrael. It seemed to them that they are eating tasty food. Whoever did not do so did not enjoy the taste of his food.
Why does it say "Achlu Lechem"?
Rashi: They made a feast - Melech Belshatzar made a great feast.
Radak: They consume My nation the way people eat food.
Malbim: This refers to Yisrael. A Midrash says that in the days of David, 100 children 1 died every day, and they enacted 100 Brachos. This teaches that in the days of David they were not careful about blessings of Shevach 2 , which stem from "v'Achalta v'Savata u'Verachta" (Devarim 8:10). We must bless Hashem for eating food. They learned from here to bless for all His benefits and Chasadim, both generation and individual. They were such Tzadikim, that for eating without blessing, they feared punishment and repented! If so, surely sinners and Ochlei Ami knew, and they totally denied Hashem!
Our texts (Bamidbar Rabah 18:21, Tanchuma Korach 12) say 100 people, but Sefer ha'Eshkol (Birkas ha'Shachar 5a) and Kolbo (1) say 100 Bachurim (young bachelors - PF).
What is his source? This was before Anshei Keneses ha'Gedolah fixed Shemoneh Esre. Perhaps they said all Brachos of Shevach, but did not say 100 because their 'Shemoneh Esre' was shorter! (PF)
Why does it say "Hashem Lo Kara'u"?
Rashi: They did not esteem Hashem, and in their feast they did not remember His wonders and awesome deeds, and they used His Kelim (Klei ha'Mikdash).
Radak #1: It did not cross their minds that Hashem sees them, therefore they do not repent.
Radak #2: Because they consume My nation and still eat food (i.e. they are alive; they were not punished), they thought that there is no justice and no Judge. Therefore, they stand in their evil and did not repent.
Malbim: [If Yisrael ate bread and] did not bless Hashem [they feared punishment].
