Impressive! You did a great job with the basics of horse colors and markings! I've had horses for decades and this is an awesome video for newbies. Clear and fairly concise explainations.
There is a difference between a seal bay and a brown. Seal bay has black muzzle and lightened pits and flanks. Brown is more mono-colored. Also liver is sometimes with lightened flanks, puts and throat with lightened mane and tail. This is referred as liver-chestnut.
With black on body seal or dk bay. I think he will cover blood bay and copper sorral with the section on champagne dilution. Sometimes blood bats are called mahogany too.
