Which Android TV device?
I'm guessing you want the Android TV connected directly to the hard drive? At home I use Universal Media Server on a Windows PC to play video on Android devices via DLNA with VLC as the player, but that wouldn't work unless you have an always-on PC to run UMS on.
You may be able to install a file explorer and browse to your hard drive, then play the videos that way. That's the method I use to play videos on my wife's tablet - copy video to an SD card then browse to it and open the files. Only in your case it wold be the HDD instead of an SD card.