I use a External HDD attached to my DVD player to play movies, music and watch my pictures on TV.
I choose this solution, because it was really easy. However, the only problem I encounter that bothers me, is that I have to disconnect the HDD and reconnect to my PC every time I want to add content (movies, music...).
Is there any way to connect an HDD and access to it remotely. Even if I have to buy a new one, it's not a problem. Bluetooth, FTP, anything would be fine.
I thought about a NAS, but I don't think the DVD player would read the files on the NAS as it does on the HDD.
You are kind of stuck with your current solution. Your DVD player can't operate as another computer so you can't share files across your network. A NAS might not work either as the DVD player would not be able to negotiate the NAS file structure.
IMHO, you are using the optimal solution now, unless you want to go the HTPC route.