Cathay Pacific had a camera underneath on their 777s five years ago
All Cathay Pacific Airways B777-300 series aircraft, not -200, are fitted with fuselage and horizontal stabiliser mounted cameras to aid the pilots during taxi-ing due to the extra fuselage length. Also to be able to monitor the rear of the wings, engines and undercarriage if the need arises.
CX and other airlines still have these cameras fitted today as standard fitment from Boeing.
The fuselage camera is what you view from your seat monitor and see the NLG doors close just after take-off...into a cloud.
I remember the old reel films being loaded into the zoned ceilings of the early BOAC B747-136 aircraft, no pause button then!
The air tube headsets were £1 to hire for the trip
TW