Thanks, Edge was ok, reset Chrome but the problem is still there. FIX: I had the chrome://flag "Force color profile" set to sRGB due to a previous issue where all the bookmark icon's colours had gone weird. Anyway, that flag is back to default and all is well.  
Inspiron 3020 i7 using on-board graphics. Watching YouTube in standard mode, I have good contrast, everything looks good. When I go full screen... once the scrub bar disappears... the brightness ramps up and it is washed out. I've looked at the Intel Graphics Command Centre and everything is on default. Is there a specific brightness control just for videos that are in full screen? Any ideas?  
Inspiron 3020 Brightness increases when switching to full screen YT video