Comparator does not give off steady signal when measuring items flowing through Hoppers. It seems to turn on and off as each item flows through; this is broken.
This makes cart unloading stations and other dropper-hopper-comparator combo builds basically impossible.
Comparisons:
MCCE Xbox One: https://1drv.ms/v/s!AmZge0rbDU70gdMUfSvtlinLjyFONg
MCPE Win10: https://1drv.ms/v/s!AmZge0rbDU70gdMbFtkNr6RbC29uxA
Your setups are different in the two videos. The Win10 video shows intended behaviour. The comparator measures every item in the top hopper that passes through it.
The Xbox One video also shows intended behaviour, but in that setup the hopper is pushing the item as the same time as it's pulling an item, which causes the hopper to never be empty, which is why the comparator is always measuring (always lit up).
As a side note, in Java, with the Win10 example, the comparator won't measure anything (which could be considered to be a bug, but in Java).