Why is YouTube and VLC making a slight but noticeable mess of my video background?
This is a problem that drove me crazy...

Long story short; certain browsers; whether it's Chrome, Explorer, Firefox, etc, actually handle color profiles, embedded within the video file (such as color workspace), differently. 

I believe if I remember correctly, Chrome uses Monitor Color, sRGB. Regardless of your video file's color profile/lack there of. 

I ran into this problem consistently, and after a lot of testing, researching, my final conclusion is that there is no way to guarantee final color values of outputs when played within Web Browsers. 

This also works backwards; because if you were to download the video file/rip using a rip tool (it very well might and include the color profile); which when played in AE or PPro would be recognized and applied; thus it would not match what you see in Chrome. 

Your best bet is to make sure your Color Space is synced through Bridge, your monitor is calibrated, preferably with a spyder, but unfortunately, regardless of your file or your system, certain players; specifically browers; ignore coloremetry data; or worse, may convert or change your settings; with no work around. End users of course; you have no clue what they see... too many variables.