I looked around the internet for Flash Gordon the greatest adventure vhs.

Yahoo japan auction does not list any animated Flash Gordon LDs for sale.

Then I found that the only Flash Gordon animated movie videos on sale are the bootleg VHS to DVD copies on ioffer. I would rather buy an official DVD, LD or VHS.

Someone put together a very nice custom DVD cover for their Flash Gordon animated movie bootleg.

http://www.cdcovers.cc/view/296852/front/flash-gordon---the-greatest-adventure-of-all---animated-custom

And I found a blog that posts a magazine article about the Flash Gordon animated movie.

http://starlogged.blogspot.ca/2012/07/1978-filmations-flash-gordon-in-future.html