A good overview of the country is Samples of Belize & Tikal, filmed in 1998 by a couple in Canada who also do videos on Costa Rica and a few other places. It covers 15 or so areas of Belize, plus Tikal. Production values aren't as high as on some videos, but it does give you a good idea of what to expect. We sell it for US$29.95 plus $3.75 S/H (ship by Priority Mail within 24 hours) in our Caribbean Coast Catalog (http://www.turq.com/equator
or Marty's store site here).
There's also a new video from Bill and Claire Gray (who wrote the Belize Retirement Guide) which interviews people who have moved/retired in Belize. This would only interest those who are looking to relocate to Belize, not just travel there. I just got a review copy and don't have pricing yet, but imagine it's around US$25.
Belize First Magazine http://www.turq.com/belizefirst/