As @lajamerr tries to clear up, "chromecast" has now fallen victim to google's incredulous renaming/rebranding tradition.
Chromecast is now either the action you take to "beam" from your handheld device to a TV or an AndroidTV/GoogleTV/Chromecast hybrid device.
Just went to the google store to find a link for you and had some trouble finding what I'm talking about and apparently chromecast devices are now considered part of the Nest family complicating things even more.
Edit: I stand somewhat corrected... there still is a chromecast device that comes without AndroidTV. I guess this just further illustrates my point about how bad/confusing google's naming and branding strategy is.
The newer Chromecast(Chromecast with Google TV) has a redesigned Android TV interface with a smart remote. The older chromecast you didn't really have any interface to interact with it aside from sending a signal from your phone to control it remotely.
In this case I believe the above commenter was just implying to use your home PC as your Media server, install VLC on the Chromecast with Google TV, and then play the media back on the Chromecast via the Network share.
Yes, a raspberry pi with a usb drive running samba and minidlna.
I started with an old nslu2, the pi on my network is slug5, as its the fifth machine that has done this job over about 15 years or so.
VLC installed on the chromecast works well with the little remote control, so local media is no harder than netflix or prime.
Edit: the original streamer I used was a Neuston mc-500, which could access network files. The nslu2 was a little slow, but 15 years ago media files were much smaller too. You could record digital tv with a usb dongle and play it back on the neuston which amazed me at the time.
Edit2: the kids had hacked PS2s in their bedrooms that had media players on them that pulled data from the nslu2 as well. It was cool, cheap and worked well.
Chromecast nearly cracks this problem, but playing local media has always needed weird fragile browser extensions in my experience.