this is another seasonal trick, this time with YouTube.
You must have noticed the Icon on all the YouTube videos which looks like a snowflake. :
When you click on it, snowflakes will start falling on the video screen and collect at the bottom.
You can also move the snowflakes on the video screen, by moving your mouse here and there.
here is a screenshot:
as you can see, a lot of snow has gathered at the bottom. and snowflakes are still falling down.
You can stop it snowing by pressing the snowflake button once again, and the snow will be gone! 🙂