This very short video shows a basic arm-roll drill. The footage comes from a seminar I taught in the Netherlands in February of 2015. This drill comes from my training in Judo, but it is now a part of my karate too.
It should always be kept in mind that, despite common misconceptions, karate is not an unchanging art with a direct line back to a single source. “Karate” is in fact a cover-all term for a wide range of systems that came to be practised in the geographical location of Okinawa.