Open video links on the internet are getting harder and harder to come by, but if you find one, you can paste the URL right into a playlist item. Most sites aren't that generous anymore though, and often require re-hosting their content. ReelSync doesn't offer such a feature at this time.
Since open links are so hard to find, the best way to get them is to host them yourself. ReelSync supports integrating with Sonarr and Radarr, two popular PVR solutions. It can also integrate with Volyar, a server which transcodes video for the web and indexes your content. Setting these services up isn't exactly trivial, but there's a wealth of information out there, including Docker containers which do nearly all the work for you. Still, the task isn't for the light hearted, and you should have some technical skills.
If you feel up to it then go rent or buy yourself a server, set up sonarr/radarr/volyar, and key your volyar URL into a ReelSync api integration. You'll also need a path mapping between your public webserver hosting the video files and the actual path on your webserver that the files live at. You can then direct your sonarr/radarr to keep your playlists up to date with a web hook. Just point it at the "Sync URL" found on your api integration's configuration page.
The player allows multiple simultaneous sync sessions through the use of batons.
Each baton holder can be followed by one or more other users. Anyone following you will get their player synced to yours.
If you're hosting a show: