I’m still looking at the other suggestions, but so far the Plex seems to fit the bill. Others may be cheaper though.
Plex works good but has some drawbacks. It won’t stream video in .iso or Video ts formats. I have over 500 movies in video.ts folders that it won’t stream. In my case I set it up to use it with my Roku box and when I played the movie it started playing fine. What happened though is that it plays the first .vob file inside the folder and then stops. Some movies are broken up into multiple .vob files and that means you can’t watch the entire movie. What I had to do is use a third party recode program like “Handbrake” to put it into an MP4 file. It takes a long time to convert a lot of movies but it works well.