Preloading is a feature designed to save bandwidth and improve performance when streaming in areas with low signal strength. Basically, YouTube will cache videos you want to watch on your device so they will play smoother later on.
The actual video pages have been changed as well. As you can see by the screenshot to the right, there are no longer individual tabs for the info, related and comments categories. Those sections can now be reached by scrolling down the page.
YouTube also puts recommended videos on your feed by default. If you don’t want to see those, you have to go into the settings and indicate you only want to see uploads from channels you subscribe to.
Lastly, there’s an option to save videos to your YouTube TV queue.
Download Link [YouTube]