I always use my "stitch-in-the-ditch" foot and also use it for joining batting together. You can just hold the 2 pieces either side of the flange and join it with a zig zag.
Hope this helps.
Anne

Gayle,
Could it have been; Name That Stitch, by Libby Lehman?
The episodes are under classroom on the purple bar at the top of the TQS page.

Gayle, it might have been Bernina's Spanish Hemstitch foot, #47. You can see more about it at http://www.youtube.com/watch?v=-a8hDBQKJXU especially if you want a small space between the two pieces of fabric. If you want raw edges side by side but without any space between them, you can also use your regular edgestitch foot #10 and pick a regular zig-zag or decorative stitch of your choice from your machine. Hope it's what you're looking for...

Gayle, I'm not sure what video you are talking about, but I use the Bernina #10 EdgeStitch foot for joining fabrics like that.
I just use a zig-zag stitch to join two straight edges, keeping both fabrics aligned with the blade of the foot.

http://www.bernina.com/en-US/Products-us/BERNINA-products-us/BERNINA-Accessories-us/Presser-feet-us/-10D

You might check with your local dealer to make sure that's the foot you need for your project.

Have you tried checking the Bernina classroom on the Daily Blog page?
I don't recognise the foot you are describing, but then I would use one of my satin stitch feet and do a 3 step zig-zag stitch to do what you are after.

I recently saw a demonstration of a sewing machine foot on this site, at least I am hoping it was this site. I
have been going crazy looking to find it again. I hope you can help me. It is a machine foot that sews
two pieces of fabric, such as wool, to each other by abutting the raw edges to each other. In other words,
they are not one on top of another, but they are laying side by side and the stitch, if I remember correctly,
kind of X's the two pieces of fabric together. Can you help me with this? If you know, what is the name of
the foot that is used, or am I having an hallucination and nothing like this exists? Thank you for any help
you can give me. Gayle