Re: Kashima shinryu
Yes, that is Paul Smith from the Tetsushinkan. He studied swordwork for a short while with Inaba Sensei and aikido with Yamaguchi Sensei in the 1980s, while he was in the BAF and working at the London School of Contemporary Dance. I understand he still has regular contact with Inaba Sensei and invites him to his dojo. I haven't practised with Paul for many years, but I always found his aikido interesting, as it is strongly influenced by his day job as a professional dancer (you can see this in the warmup in the first video).
Kanetsuka Sensei was also strongly influenced by Inaba Sensei for a while, firstly through the late Sekiya Sensei (who studied with Inaba at the Shiseikan), and then through direct contact with Inaba, whom he used to describe as a kind of martial arts prodigy. The connection with Yamaguchi Sensei is also significant, as many of the latter's students (for example William Gleason and Christian Tissier) also teach this style of swordwork.
We used to practise the Kihon Dachi regularly at Kanetsuka Sensei's dojo in Oxford in the early 80s, although he never claimed he was teaching KSR. I feel that the way of using the sword in these exercises is very relevant to aikido, and is very different in essence and feeling to the "aikiken" taught by Saito Sensei. These days Kanetsuka Sensei hardly ever teaches swordwork, and certainly hasn't taught the Kihon Dachi for many years, although Ken Marsden does teach it at the BAF Summer School.