Tani otoshi video
Info about "Tani otoshi video"
Tani otoshi (valley drop) is one of the original 40 throws of Judo as developed by Kano Jigoro. It belongs to the fourth group of the traditional throwing list in the Gokyo no waza of the Kodokan Judo. It is also part of the current 67 Throws of Kodokan Judo. It is classified as a side sacrifice technique (yoko-sutemi). With the tani-otoshi you place your leg behind both legs of your opponent while still holding him in you favorite komi kata and pulling the opponent backwards resulting in your opponent falling on his back and you falling sideways. 
Tani otoshi can be performed in many ways, referring to the drop of someone falling from a cliff backwards, the English for this technique helps the ‘pure’ way that this technique is performed – tori steps behind the uke, both legs performing a ‘V’ shape, one leg in front and one behind. 
From Wikipedia  and Akitas Judo