format tag 2000 means your audio is AC3 encoded (up to 5.1 channels) and since you don't have AC3 codec installed direct-show based media players are not able to decode the sound. Usually that codec comes with software DVD players like PowerDVD, WinDVD. Alternatively you  

can install a free one, for example, AC3 Filter.  

If you want to join the scenes you obviously need all audio tracks to have the same format (either AC3 or MP3). Quick how-to on converting AC3 to MP3: save AC3 track using AviDemux, decode it to several mono WAVs using azid (use downmixing to 2 channels if needed) then  

encode those WAVs to MP3 as usual.  

Hope that helps.