On the client side setup couldn’t be easier. Just grab the installer from https://jamtaba-music-web-site.appspot.com/
If you’re familiar with Linux, setting up a NINJAM server is simple. You can also use mine at beepboop.fm port 2049
Jamtaba includes webcam support but it syncs with your music, which is intentionally delayed in order to make things sync (with an offset) at the bar (for whatever definition of “bar” you might have). This means you will be hearing everybody else’s prior “interval” (NINJAM term) while you play your current one.
Before you play you agree on a BPM and a BPI. BPM is a familiar concept. BPI stands for beats per interval. I often pick 8. There are reasons for making the number larger or smaller depending on genre and intent.
It’s an approach that works well for repetitive or cyclical music. But you aren’t going to be seeing your friend’s hands in real time. The beats will be synced, but you will be seeing and hearing their past, and they yours.
Sounds confusing but for many common types of electronic music it just works. You really don’t even notice the delay because things are in sync.