HG refers to Hustlergirls.com.
This is a Totem-based website similar to Virtuagirlhd.com.
It seems now that everything on the two web sites is identical except the background.
edit: Also, if you download hustlergirls, you can add that to the vghd program. Both web sites work in a single program.
With this, you can get twice as many trailers (five from each web site).