GravityAPBTs' YouTube channel (many dog vids)
Kennels
In light of everything going on, I no longer recommend other kennels. If you are looking for a breeder, please do careful research to avoid heartache. Look for a breeder that is open and transparent. Demand a minimum of health-testing, especially genetic panels to identify carriers of less obvious diseases like progressive blindness and hyperuricosuria. (There are good groups on Facebook for health-tested APBTs where you can get more information.) Seek breeders who are active with their dogs in some kind of events, if at all possible. And ensure that they will take back one of their puppies at any point in its life, if the need arises. Best of luck in your search.
Dog Supplies
Brown Dog Design - Weight pull harnesses, collars (Highly recommend)
CD Pits - Highly customized weight pull harnesses, walking harnesses
Texas Tripe - Raw dog food in the TX/OK area
Rogue Pet Science - Awesome supplement
Collarmania - Custom nylon/ribbon collars
Ella's Lead - Rope leads and super blingy leather collars
BashTo - Heavy-duty dog gear
Gun Dog Supply - Good leather collars and other gear
O'Brien's K9 Supply - Breaking sticks, collars, harnesses, etc
Overtyme Kennels - Awesome cowhides and other APBT supplies
Paco Collars - Custom leather collars/leads
Scout Dog Collars - Custom nylon collars
APBT Information
United Kennel Club Breed Standard
American Dog Breeders Assn Breed Standard
American Kennel Club AmStaff Breed Info