Not a great video, but the Q50 has the same single motor two clutch hybrid system as the m-class. Around the 1 minute mark you can get a quick glimpse at how this system works. From my general understanding:
1) Front clutch eliminates torque converter and is used to de-couple the engine during EV driving.
2) Rear clutch allows for stationary charging and torque smoothing (ex. starting the engine without disturbing the rest of the torque path).