NOTE: post edited by me for adding more info
In addition I would advise you to don't edit settings of different extensions at the same time, just one by one and in between do some test and see if things are different, I mean in an eliminating manner. If the editing and in between tests don't make a difference, please change the edits/settings back to what is was before. Or else it can be really confusing and afterwards you can probably loose the lead on what exactly the fix finally could be.
Your code is correct and will work properly (just try to decrease the &amp& to a minimum of & or just '&'. The editor will automatically correct this to &. So don't focus to much on the code, I've tested it and works in either way, whether there are to much ampersands in it or not.
I've put my Artisteer site online for you to compare. Excuse me, it's only in Dutch but for the use of Ninja Shadowbox it doesn't really matter :).
Your video is on the frontpage (you've to scroll a bit).
I think the problem has to do with some conflicting by different preloaded scripts.
As far I can see, the scripts for Ninja SB are just partly and not properly loaded.
I also see an JQuery error related to Ninja SB, this is caused by JCE Mediabox and JT Slideshow (and may be other extensions) are making use of the same library which could be conflicting and that's why I suggest to change the Ninja SB library to Dojo or temporarily disable JCE Mediabox and JT Slideshow.
I will try to test what's happening when I install JCE Mediabxox or/and JT Slideshow.
Oh...the border (that you don't want surrounding the preview) is probably created
by the image's css style regarding the 'block' defenition.
Just add border: none; to the style tag.
And like Mark said it could be an Artisteer issue.
I'll keep you posted.:)
I hope you can make something out of it.
If you still having trouble, please let us know.
Greets ;) ,