... I think there is some relation ... but I don't think, videos of Endo sensei will help to get into internal practice.

here is a video of Ikeda sensei talking about using breathing to aid your movement http://www.youtube.com/watch?v=4hB-knlRDZ8 using close and open body through breath

or this one http://www.youtube.com/watch?v=St7I0M2fx1c for dantien/hara movement

or this one http://www.youtube.com/watch?v=0K3a9Z5DZnc - which sort of an SJT (stupid jin trick) where jin does not depend on structure. demo, not necessary training.

or this http://www.youtube.com/watch?v=epfWXEuEgYI - sort of basic "four-legged animal" and i am the control end. demo, not necessary training.

cross reference this http://www.youtube.com/watch?v=SP9FoeyLjDo with the aiki-taiso exercises
first movement is similar to open-close body to Ikeda video (tekubikosa and johokosa undo)
second movement - funakogi undo
third movement - ikkyo undo
fourth - sayu undo

problem is video won't show you what all the gazillion things going on inside the person body that the person is focus his/her intention on.

But without more context I'm not sure how helpful they'd be.
And all things considered I suppose there's nothing else I can tell you other than wishing you luck.

I agree with Hugh, what you can see in video is generally not that useful unless you already know what to look for to some degree. We've got lots of video of Ueshiba and it doesn't seem to help folks all that much.