I have 5 computers in this RV all networked via a standard Home/Small office Router, at the moment a Belkin but I've used others in the past. I DO NOT RECOMMEND BELKIN. 
ONE is a 100 dollar windows 7 Referb "Desktop" from Target.
I also have two REPLAY TV units and a Chromecast 
The Replays have a problem. they don't have nearly enough hard drivem when I'n in a well covered (TV WISE) area I tend to fill 'em up and have to "off load" to the win-7 box. from there I can copy or move videos to any other computer device, my smart phone or tablet. all can handle the video format the Replays use. 
Or I can stream back to the replays or to the chromecast or.. Well you get the idea.
The magic is the software. THe software I use is specific to the Replay but ...
Casting to a Chrome cast can be done by many different software packages if you have the casting extension installed.
I assume this is true of most other video clients as well but not having them that is an assumption.
Finally. There is a computer.. Now you have to do a bit of "Work" to use it but Raspeberry PI
The original Pi's and every one since has the ability to play videos from any source you can "Download" from.. I have a PI but have yet to assemble and program it, This is a linux box but it should be able to play videos stored on any of my systems.  Provided it is connected to my router.