There is some information on CMS widgets in the manual (search for 'widget'):
https://www.vbulletin.com/docs/html/ Lots of other stuff here and at vb.com. Assuming you have the suite, of course.
Post 77 may refer to some specific tweak to the embed code given at this particular crossword site. However, it has not yet been shown that this one is still active. I uninstalled it 3 years ago when it stopped updating. The spam I was refrring to would be a site that surrounds the crossword with annoying ads or sends you a deluge of emails.