What is it?

NMBgMonitor.exe is associated with Nero Vision; Nero Home and Nero Scout multimedia applications.

What does it do?

The word is that NMBgMonitor.exe is Nero Media Background Monitor. Although that title is just speculation,
there is a notion that the file is part of Nero Scout media monitor. This app constantly checks for new
media files such as .mp3, .avi and .mpeg etc... so that it can create a database of available media files for easy access.

This might create bottlenecks or use up system resources. If you don't use the Nero Media database you might free up
some cpu cycles and memory a little by turning it off.

More info:

Read more about Nero software @ nero.com