.dat files store some stream information, but you can't play them with Windows Media Player like .ASF, .WMV, .WMA files.

I don't have the Windows Media Stream Editor. I watched the file properties with Media Player Classic. It showed one audio track only.

And I perfectly know that NetXFer was able to select a single bit-rate in a zillion of times when I was recording primarily Real Video streams. I bet all other media stream recorders do the same.

To test it you may use WM Recorder in PRO or ADA mode. In these mode WM Recorder captures packets from the Windows Media Player.