2 engine a/c are massively over powered for obvious reasons. MIA-Doha is a long way = heavy a/c, but the performance is calculated assuming losing 50% of thrust, which they did not. Therefore one would expect the a/c to lift off and clear the approach lights of the opposite runway by considerable more than 35'. So what happened & why? To suggest they did not know is one thing, but I'm sure there were more than sweaty palms as they hurtled towards the end of the runway. There is more to this than is being reported here.
Remember the Russian freighter in Aus that cut the grass in the stop-way? ATC were encouraging it to fly. This must have looked something similar. I'm amazed if ATC didn't call for a light inspection and inform the crew. Surely they have tell-tale monitors in the tower for the lights status?
There are also lots of spotters at airports such as MIA. I'm sure there is a video somewhere that will burst on to the scene.