In this particular case, I was semi-brain dead and wanted to edit the BBCODE to eliminate everything but the actual image URL. As I indicated, I failed for some reason to remember to just insert the darn BBCODE into the edit window.

In the grand scheme of things, I realize this is a small issue. Still, it seems to me that simply pasting text into a text field should not automagically submit the form. It is simply bad UX behavior. The user should have to click a button or hit RETURN to submit the form.