The difference may be in kilobytes versus kilobits. DUMeter seems to use "kB/sec", although the standard is generally either "KB/sec" or "kb/sec". I'm not sure if their use of "kB" is meant to mean bytes or bits.

Regardless, I recommend using Ethereal ( http://www.ethereal.com/ ) to check out what the actual traffic is. It may be UDP, it may be local (to/from your computer), it may be the iTunes sharing, etc...