Chrome/Youtube/Hardware acceleration

Has anyone noticed that if you turn off hardware acceleration in the Chrome settings, YouTube videos kind of lose a bit of luminance and contrast? It's been driving me nuts going back and forth between the two deciding if there's a difference or not. I really think there is and I don't know why that would be. They have a sort of washed out look if you turn hardware acceleration off. I turned it off because I'm designing a video header for my new website and noticed that if I had multiple Chrome tabs open with the video playing, the playback got really choppy and so I found that turning it off fixed this. Then my girlfriend last night said she reckoned the video looked too dull and that maybe I should adjust it. So off I went into Premiere to add some luminance and it looked great in that app, and great when I exported it and played it in WMP, but as soon as I uploaded it to YouTube I noticed it looked all washed out again, totally different to how it looked before. Here's the same video side by side, on the left in YouTube and on the right in the Premiere preview window. What a difference!
 

 
Should hardware acceleration actually affect color and contrast though?