Make sure that network access for all devices is allowed.
- In Windows control panel select Network and Internet -> Network and Sharing Center
- Then click on Change Advanced Sharing Settings in left panel
- Make sure Turn on network discovery is selected
- Scroll down to media streaming and click on Choose Media Streaming Options
- Change Show Devices on from local network to All Networks.
- Click on Allow All
- Click OK, and then Save Changes
PlayTo should then work to any device that is a digital media render(DMR). According to the blurb in the instruction manual it looks like your BD is a DMR, so it should work.
The files must be in a compatible format (eg mp3) for your BD to play them. If they are not you could use a transcoding mediaserver like Tversity instead of WMP on the laptop.
Digital Media Players (DMP) are not as fully-featured as they can only pull music from a server, you cant push stuff to them.