Not really. In fan fiction writing, a beta is someone who gets to preview the work first, but they have a job to do and that is to find any mistakes that the writer has made before posting the story, or submitting it to a 'zine for publication. A preview, if you're thinking what they do with movies, is to put the work out there for a limited audience to get their reaction.
Think 'editor' rather than 'beta' and you'll get an idea.
Cheers,