Acrylic mediums are not actually made for textile use. They're main use is by painters and they have been adopted by textile artists right along with acrylic paints. There are all types...gel mediums, crackle mediums, texture mediums, glazing mediums, and so on...all for use with acrylic paints. Fabric and textile mediums are different.
There is a wealth of information on the Dick Blick website, including videos on almost everything you can imagine. Here's the section on fabric painting...videos are at the bottom or you can just click on the video icon.
http://www.dickblick.com/categories/fabricdecoration/
The site is very easy to navigate. Want to see how Shiva paintstiks work? Select S from the directory, click on Shiva in the brand list on the right side of the screen, click on the video icon or page down and select the video.
It's that simple. It's a superior store, too, btw.