I had the same problem, but after some fiddling round I can now play back recorded TV in Windows Media Player.
As you can play from WMP to the recorder, I'm assuming your network is setup OK?
This is what I did (I am on Windows 7, 32-bit, using WMP v12):
Open an explorer window. Click 'Network' and you should see DMR-HW120 under Media Devices on the right. Right-click the icon and select 'Media streaming options'
Select All Networks, from the 'Show devices on' option drop down.
You should see, amongst others, icons for 'Media programs on this PC and remote connections' and 'DMR-HW120'. Make sure that you select 'Allowed' for both these options and press OK.
Open up WMP in normal view.
Under the 'Stream' option, I have 'Allow remote control of my player' and 'Automatically allow devices to play my media' both ticked.
On the left, you should see your libraries, and towards the bottom 'Other Libraries'.
Under this section, you should see 'DMR-HW120', with a + sign next to it.
Expand this and you have options for Music, Videos, Photos and Recorded TV.
Select Videos, NOT Recorded TV and you should be able to see your recorded programs.
Right click on a video and select play. It will connect to the recorder and after 10-15 seconds, should start playing your video.
YOU CAN ONLY PLAY STANDARD RECORDED TV. HD RECORDINGS WILL NOT PLAY.
Hope this helps.
I have tried setting up a LAN between a Panasonic DMR-HW120 and a Acer laptop running Windows Vista Home Premium.
I can get the laptop media files to appear on the HD recorder (using the HDD as a client) but the other way (using the HDD as a server) around it is a problem.
If I call up the window for 'Network' it shows two instances of DMR-HW120. If I click on one it brings up the Media Sharing option in Windows Media player but won't show any files from the HD recorder in Windows Media Player whatever setting I use. The other instance just shows the properties such as the IP address when I click on it.
When the laptop is connected and I call up the Direct Navigator on the Panasonic HD recorder it does display a warning next to some HD channel recordings that these can't be viewed via the DLAN. However, I have other media which doesn't display this warning.
Any ideas for viewing the HD media on my laptop?