The Reverse Reverb is not one of Moselle's built-in modules. Instead it's a user-defined module, which contains inside a Delay and some Filters. It uses the delay without feedback. Instead, it randomly distributes the number of taps you specify according to the time parameters you give. Here, we hear 400 taps from 10ms to 2.8sec. (This is edited part-way through the video to 800ms.)
The knob adjustments simply tweak the module's low and high frequency filters.
Note the sound is recorded directly from Moselle: no hardware or external processing was used.