Salam
Such 'nazams' are leaving the boundaries and becoming like the music of the kuffar. This is a new tribulation upon the muslims and a sign of the last hour.
May Allah protect us
Wassalam
I listened to the nazm/hamd/naat/nasheed (not sure if there is difference in meanings of these words) or whatever they have on banglakitab.com and did not find any instrumental music. They are just words. Since I do speak Bengali without local dialect, I was able to understand them. They sounded like poems with emotion. I contacted the admins of banglakitab.com and they said that they had A LOT of these and they are only offering the ones that do not contain bidat/innovation or disrespectful comments. I checked with the Ulema and they said when Rasulullah Sallallahu Alaihi wa Sallam migrated to Holy Madinah, the children sang a naat with drum/tabla (Tala Al... it is available in hamd/naat section of islamibayanaat.com, which was also in the movie "The Message") and hamd/naat are allowed without instrumental music, except drum/tabla.
So, I disagree with the initial comments in this post and I have verified my stance with the Ulema. I urge you to verify this with the Haqqani Ulema.
Even if you disagree with this, I think Bangla speaking brothers/sisters should take advantage of the large collection of authentic books translation and speeches on banglakitab.com . Their collection of Bangla Quran translation audio is excellent quality.