Their slogan is “Videos about numbers and stuff” and these are indeed fun, informative videos about all kinds of mathematical properties. The goal of Numberphile is to take some of the more complex and abstract mathematical concepts and make them more accessible through their video series.
Stretching the gamut from explaining about the value and properties of pi (Π) through infinity, dividing by zero, complex encryption, through how to successfully order 43 chicken nuggets Numberphile has close to 100 individual videos available. These are all hosted on YouTube, so make sure that you would be able to show them at school – or use a converter. Videos range from about 3 minutes up through about 15, so they can be used as a supplement to a lesson or perhaps an alternate explanation of a concept you can direct students toward.
Numberphile does assume a level of competency in basic mathematical principles and operations in their videos, so this would most likely not be for lower level or struggling students.
Also of Interest – My post about Downloading Streaming Video and other Media might be helpful if your school filter will not allow access to videos through YouTube.