I *think* that 52410 is part of the DLNA application, which isn’t related to Windows File Sharing. DLNA is what’s used when you select “MEDIA SERVER” instead of Network Share. And Windows XP doesn’t have DLNA capability by default. Windows 7 does, so that firewall rule would definitely be important to a Win7 user that couldn’t access their MEDIA SERVER.
The Firewall might be blocking port 137, 138, or 139, all of which are critical ports to the WDTV.
Port 137 is the NetBIOS NAME SERVICE. This is the port that WD needs to talk through to the Windows Hosts when it asks “Hey, who is server XXXXX?”
Port 138 is the BROWSER SERVICE. Port 138 is the port with which computers talk to the MASTER BROWSER on the network. (By the way, you’re right, the ORDER in which __MSBROWSE__ appears in the list isn’t important here.)
Port 139 is the port through which the files and transports are actually carried across. File and Printer Sharing uses this port to the extreme.
So, if ANY of those are blocked, the WD will not function correctly. Off hand, I can’t remember which are TCP and which are UDP, but there’s usually no harm in opening BOTH TCP and UDP for all three ports.
