If you do a search in the Escorts section of Backpage with a search term of "couple", you'll find several couples out there willing to do a show like the one in the link.

there is a 'market' for everything.  There is always going to be somebody who has this type of fantasy.  

Just watching doesn't sound like a whole lot of fun.   Might as well go to a strip club, drop lots of bucks, and get kicked out if I want to touch the goods.

But there is so much on the net that those interested in that can download lots of videos of that.

I would need to be part of the entree.  And, of course, the two ladies could always share dessert.

As clubjeffe said - there is a market for almost anything... I would be interested....

Restaurants or strip clubs??  

Provide the guy with an attractive second girl to be going down on him while he watches

I take it that your girlfriend does not provide?  

Ok so I'm in a small minority here but I love private girl-girl shows. I've done it somewhere between 30 and 40 times and if the ladies are into it it's a blast.  I look at it like strip clubs: sometimes I want to be titillated and turned on but don't necessarily feel like jumping in.  There was even an agency here in LA that specialized in that kink. When they went out of business I was able to find some accommodating ladies on this board.  Heaven help me I just think it's the most beautiful thing.