[Plugin: Shadowbox JS] Shadowbox still opening in YouTube whichever url used

Hi
I’m trying to implement shadowbox (with youtube simple gallery) on a wordpress blog. It works fine on my test blog but on this one: https://iamscrilla.com/uncategorized/test-media it opens full screen in youtube – whichever url I use. They are flv files but choosing flv on shadowbox doesn’t make any difference.

Tried everything I can think of including all sorts of direct urls (instead of going through simple gallery) but there must be a conflict with another player somewhere.

Or is it easier than that and I’m just missing something obvious? (here’s hoping that’s the case ?? )

Many thanks.