Watching this (and all the excellrnt videos you have forwarded) - Ju jitsu looks like Qinna - or an element of Qinna. Qinna - or 'Joint Relocation' as Master Chan referred to it in Hakka - emphasises breaking bones, dislocating and/or snapping joints, but only in its highest or most deadliest aspect. The Chinese language instructional texts talk of the 'grip' being developed so that 'skin' is torn-off and 'bones' shattered like glass!
a) Ju Jitsu (柔術) = 'Rou Shu' - or 'Soft Expertise/Art'. An ethnic Chinese speaker once explained the underlying concept behind the 'Rou' (柔) ideogram to me as 'to ride in another person's rickshaw' - which I thought was superb! Not just 'borrowing' - but if need be - 'stealing' another person's vehicle of transportation (or mode of 'movement') certainly with their knowledge (after-all, they are 'present'), but equally 'without their consent' (as the resulting outcome is often contrary to that desired by the opponent)!
b) Qin Na (擒拿) = 'Catch Relocate' (Probably 'Kin Na' in the Japanese language).
Working down from that level of destruction, there is the well-known 'controlling' of the opponent through 'light' joint relocation designed to 'move' the body around (from an 'inconvenient' place to a 'convenient' place), or to 'disarm' or 'subdue' whilst leaving the opponent or assailent relatively 'unharmed'. Indeed, what makes genuine Taijiquan so effective is its inner core of guiding Qinna. Coupled, of course, with the mastering of the dropped bodyweight through an aligned bone structure - and the efficient directing of the resulting 'rebounding' force from the ground to the extremities - a process which allows for the generation of tremendous 'breaking' force with apparently 'little' effort!
Shifu Adrian Chan-Wyles (b. 1967) - Lineage (Generational) Inheritor of the Ch'an Dao Hakka Gongfu System.