Ask HN: How to market a Video Dictionary

Need your advice . Recently launched a new site - http://www.megavocab.com - Its a Video Dictionary.

I am confused about the best way to market the site. It is clearly not a SEO play since the competition is sites like dictionary.com , merriam-webster , thesaurus.com which are long established , more so this site is video something that google does not understand completely when compared to text

I am trying to hit facebook and twitter to get some traction but that is a tad slow ...

Any suggestion how can reach a relevant target market in a scalable way ?