From YouTube, produced by MuchoMath
This video indicates it is for pre-algebra, however this would be good for anyone who is reviewing subtraction. In this video they show how to subtract using the number line, this includes negative numbers. They do this using many different examples. Then they do a word problem using the number line and then equation form. Once again they do a few examples. Video is good quality and good for all students as review or initial learning of the concept.