xingcat
Be good to self.
I recently changed the way I present my thumbnails, removing the backgrounds and adding a colorful gradient to whatever I was presenting (either just a screenshot of myself in the video or whatever the video is about, like the food I'm cooking or the characters in the sketch of the week). The result frankly surprised me. I am now consistently seeing my videos gain views about twice as quickly, and they all have had a 20% increase in views across the board.
Now, to be honest, I HATE the look of thumbnails in the way they are generally presented on YouTube. I think the "colorful background with just one person or thing in the foreground and large title" look is so over-used that it's repetitive and boring, but I can't argue with the results. So if you're unsure if your thumbnails are playing a role in views, I'd say they are, and to play around with them until you find a way of making them pop enough for viewers to click on them.
Now, to be honest, I HATE the look of thumbnails in the way they are generally presented on YouTube. I think the "colorful background with just one person or thing in the foreground and large title" look is so over-used that it's repetitive and boring, but I can't argue with the results. So if you're unsure if your thumbnails are playing a role in views, I'd say they are, and to play around with them until you find a way of making them pop enough for viewers to click on them.