I made you a new video with instructions on how to make a scarf-tube out of cotton jersey.
Now that the days are not so cold you can make a scarf-tube from two pieces of cotton jersey.
For winter, however, it is great to use warm fleece for the inside.
Draw the cut on an A4 sheet as shown in the picture. For fleece, add about 2 cm in width, because it is not as stretchy as a jersey.
Me and my children really like this tube. Kids simply pull it over their head on their own and there are no problems like with standard scarfs.