why does flashplayer stop video while sound continues?

i recently updated my toshiba to win10 os. i prefer firefox and use duck duck go as well as ad block plus. i have the latest version of ff, flash player and have gone thru all the self help steps. videos play fine on chrome and ms web toolbars. i have to go to chrome to watch vids now. can flash be fixed on ff?  thx for any help.