Re: easily accessible videos of Internal Training in Aikido?
Mike Sigman had a series of three videos on "Internal Strength" years ago. I believe he pulled them from the market eventually (you'd have to clarify that with him, I'm going from a shaky memory). I do not know where you can find them today although I'm sure you could search around.
The Aunkai has a series of videos but those are really intended for their students. Like many things, without the larger context you would likely only be led astray. But I'm an academic at heart so I bought copies for myself. And I've subsequently had the luck to play with someone who had hand's on training. But without more context I'm not sure how helpful they'd be.
There are also dvd's out there showing some of Kuroda's stuff. But again they appear to be designed as supplements for practicing students. Hence again probably limited value at best for anyone outside the style.
And all things considered I suppose there's nothing else I can tell you other than wishing you luck.