50 in decimal is 32 in hexadecimal. Tag 32 is MSN Audio and I remember it used to be an automatic download from the Microsoft codec server (http://codecs.microsoft.com/codecs/i386/msnaudio.CAB to be exact), but they seem to have removed it. It's really infuriating to see them remove one codec after another from their server (first i263, then cinepak, now msn audio).
I've been trying all kinds of installs (msn messenger, windows media player, netshow tools, netshow encoder, windows media encoder, windows media codec packages, and many older versions of the all the above) to find it, but without success.
I did a manual installation after finding out what files were involved and here are the steps for Windows 2000 and XP (not for the faint of heart):
1. Google for msnaudio.acm. Download it and copy it to your windows/system32, or winnt/system32 folder, depending on your version of windows. Here's one hit:
http://neuron-ai.tuke.sk/~hudecm/d/mplayer/w32codec-0.90/2. Start the registry editor. Go to the start menu, choose run, and type regedit.
3. Navigate to this key ("folder"): HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows NT/CurrentVersion/Drivers32
4. Go to Edit, New, String Value. For the name of the value name it MSACM.MSNAUDIO. Then double click it and for value put msnaudio.acm
5. Go to the key ("folder") above that (HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows NT/CurrentVersion/drivers.desc).
6. Go to Edit, New, String Value. For the name of the value name it msnaudio.acm. Then double click it and for value put "Microsoft Network Audio CODEC for MSACM" without quotes.