It is a huge untapped market. I can recall one VERY old company who produced a F/MF video. That was about all I can remember regarding the mixed gender coupling. I am also surprised it isn't more common given what I read in the Real Stories section.
That recent thread was derailed pretty quickly due to the suspicious nature of the OP. No real discussion ever happened AFAIK
I don't know if it is a huge market. If it was, I am sure someone would attempt to exploit it. Back when I uses to buy tickle porn, I never saw single */fm video.
The only one I can recall was a vid tickling paradise did a while back where a cheating husband and his lover were tied to a bed and tickled by the wife. Great vid and definitely planted the seed in my mind of how fun it would be to tickle a couple.
I have seen and reposted the vids of your wife being tickled on tumblr (mine's captureddoll) I love her laugh and the way you tickle her feet with feathers... nice to see the face behind the camera. Maybe someday I can help you make your fantasy come true... I LOVE this fantasy too!!! But first gotta get out of our financial debt. It has to be our priority right now.