After starting random video from sites like for example YouTube and Vimeo, smartphone (Samsung Galaxy grand neo) begin to lagging for a moment while video frame display loading symbol. Afterwards symbol disappear and screen turn black while sound plays correctly. Problem first appeared after I had updated FF from version 35 to 36 and its also visible on freshly installed FF37 beta. Strangely, on device default browser and chrome everything works fine and w/o any lagging. I tried to resolve this by turning off hardware acceleration in browsers settings, install specific addons(5html everywhere) and even reinstall FF36 and FF37b but nothing helped. Any idea how to fix it will be highly appreciated. Cheers.