I have not see any indication that there has been any change in ownership - she's still using British call-sign and MMSI, it seems. It's probably an over-enthusiastic courtesy flag in French waters.

By the way, the official registered name of the ship is PHOENIX OF DELL QUAY (the British registrars are more restrictive nowadays about avoiding duplicates on the same register)
Square Sail Ventures Ltd (Deep Blue Events Ltd organise the film work) - both companies owned by Shane McCarthy. Apparently still based at Charlestown, Cornwall.
GBR flag, reg Portsmouth, ON 701300, c/s MMZV3, MMSI 232003971

Looks like she's flying the French flag now. Does anyone know where she's based out of?