Don't know which "ferrite rings" you mean but I see
these, which are not petite but relatively large toroidal
power inductors.
Perhaps this inverter works "Class D style" and does
not boost raw positive supply at all, so no "housekeeping"
DC-DC. It could happen, no way to say whether or not
without a much better look at the guts (there's like 2
frames in which you can even get a look at these fat
toroids; who knows what the videio doesn't show?).