Mini player and Picture-in-Picture
Keep watching in a corner while you browse for the next thing, on every plan including Free.
Leaving a channel to look for another one used to mean stopping it. It does not here.
The mini player
Back out of a stream and it shrinks into a corner instead of stopping. Keep browsing categories, the guide or Movies while it plays, then expand it again or close it.
Picture-in-Picture
Leave the app entirely and playback follows into a floating window, where the device supports it. mtivi never gates this, on any plan.
One video at a time. The mini player and the full player share a single video surface, so starting something new takes over the window rather than opening a second one. Multi-View is the feature for several streams at once.
On a phone
Picture-in-Picture is most useful on phones and tablets, where it keeps a match running while you use another app.