DVD or video
Who (where) is your market? The answer to your question is, in part, a function of your publisher''s distribution and marketing plans before it''s a function of VHS vs. DVD.
I think it''s fair to say the U.S. is, with a few exceptions in the Far East and Western Europe (essentially Scandanavia & Germany), well ahead in both the widespread deployment of computer useage in the home and also use of DVD technology for home entertainment. If you''re hopeful that a significant part of your target audience is in the EU and Australasia, VHS is an important media of choice, at least for those areas. (And you''ll need to think in terms of the different formats).
OTOH if the predominant audience is American and in the near term the publisher is willing to forego potential sales from those other regions as well as some U.S. sales, DVD is the coming thing. (In which case, the ability to play your program will be affected by Region Codes instead of formats).
We (globally, not just in the U.S.) seem to be in another of those technical transitions (remember Beta VCRs? 8-track tapes? 5" floppies? even computer zip drives are becoming passe now...). I notice many products today are offered in both formats; that would reach your maximum audience...but may not be as lucrative for you & your publisher.