Plex is a free app that lets you stream your media collection to every device you own. Plex will convert and stream video files and music files. It creates optimized versions for mobile devices.
To set up Plex, you install a Plex Server on the computer where your media is located (preferably a desktop computer). Once the Plex Server is running, you’ll be able to stream your media to the Plex Player app (also free). This app is available for mobile devices and a range of smart televisions and streaming players (like Roku).
Also available is the PlexPass service, which allows you to download your content for offline viewing. The cost is $5 per month.