YouTube introduced preview thumbnails
So a little (important) update that we have expected from YouTube well since it's launch.
You can now see a preview thumbnail when you put the cursor over the charged content.
For instance if you are at 0:21 and the video is fully charged and you put the cursor over 0:40 you will see a preview image of the video of how it looks at 0:40. Sweet!
Things like that existed on other video websites for years but YouTube is a huge website where is really hard to implement new things.
And now here is a video where you can check the new thing out: