Information about Martial Art

What is Boyovyy Hopak? Video on ukranian folk dance and martial art:
http://youtube.com/watch?v=huKyHxHi-04

Kazaki (Cossack) folk dance and martial art training:
http://youtube.com/watch?v=hTmVJYSd7t0

Kazak (Cossack) dance tricks and lower body muscles trainging:
http://www.youtube.com/watch?v=3xPaVxMWr1c&feature=related

Russian Specnaz (Special Forces) System:
http://www.youtube.com/watch?v=JfRtRB72QuY&NR=1

Ninjas: Art of Japanese folk
http://www.youtube.com/watch?v=XIY_8ylGni4