I would suggest a link on your blog "WRITE AN ARTICLE!" or "SEND A VIDEO!"

Given the scope indicated, there might be a few interested in participating!

Otherwise check locally and PAY for new content to be written.

Better yet, write it!

Yes, you could always advertise at ProBlogger or any freelance writing site. Or do a Google search for article writers in your niche, or Craigslist - the list is literally endless.

But be prepared to pay, particularly if you want expert and QUALITY posts that don't dilute your own expertise (or image).