Invisible YouTube buttons on Firefox 42

Hi Kevin,
I found some problem after update Firefox to version 42 – when I want to play YouTube video on my blog – the navigation buttons are invisible.

Example here: https://gracz.org/wp-content/uploads/2014/03/yt-bug01.jpg
and on my blog: https://gracz.org/premiery-gier-pc-listopad-2015/

The most strange thing is – everything works perfectly on FF Private Mode.
Disabling LLFV also solves the problem.

Greetings,
Adrian

https://www.ads-software.com/plugins/lazy-load-for-videos/