FF v5x ESR, hmmm.. probably only FF v52 ESR, so, probably in one year this "ESR" workaround won't be the solution anymore.
And same problem with Chrome : i can't do the "enable NPAPI" workaround with my chrome version 57.
NPAPI is a technology born in the nineties.
Who is to blame ? Chrome and firefox ?
Noooo : before they do this, for good reasons, they warn long before to do it (example : Chrome annoucement in 2013!), and when they do it, they do it progressive (first a trick is possible, then not possible).
Dlink should have work on the subject since 2013, but probably they work on this only now.. If they really work on it.. Maybe they think that they can just require FF 52 ESR and then in 2018 Q2 they will say "buy our new dlink camera"..