Viewing Youtube using IE.11 & Chrome, when you hover over the Channel name, a popup lists the # of videos (Video Count) in the Channel -- FF 48.0.2 does NOT -- see the image -- IE.11 is the top image & shows the desired functionality, FF is the lower image & does NOT show the desired info in the tooltip popup. This is a must-have functionality so that I know how far down to drill to search through "All" the channel's videos when viewing their page under "Videos" tab. I disabled every addon/etc in my fresh install of FF 48.0.2 but that didn't solve the issue.