Shauna Sand says her Frenchie ex-boyfriend doesn't have a leg to stand on -- specially the third one particular -- in his lawsuit over the launch of Shauna Sand sextape -- and ironically what kills him is an additional online video in which he admits he knew precisely what he was carrying out when he signed up.

so he's suing the greatest porn provider in the globe.

Antoine Berlier claims in a new lawsuit Vivid Enjoyment screwed him out of huge income from his video with Shauna -- whom he refers to as "a prominent American intercourse symbol."

And in the self-aggrandizement division, Berlier claims he was of "huge value" to Vivid, and not only due to the fact that of "natural attributes."

Vivid honcho Steve Hirsch tells TMZ, "We have a signed, model launch and this footage will continue to be sold." Hirsch also states Berlier knew what he was signing and Vivid has the video clip to prove it -- of course.