The way I see the Judo throw it is a variation of Kani-Basami, flying scissors. It is illegal (in both Judo and wrestling) if you use both legs to scissor. The variation shown is to reach back with you arm instead of the leg. As G&P stated it is a common wrestling "clinic" technique to counter a single leg, meaning a technique that looks good in a clinic but has a low percentage chance of actually working in a match.
http://www.judoinfo.com/images/nauta/kanibasami.htm