Each of their videos are between 2-4 minutes and highlight the essential things students need to know. They seemingly have hundreds of videos on almost every major person from World and US History - including some that are hard to find good information for.
For example, here's one on Robespierre for my World History II students:
Or Susan B. Anthony for US History:
I posted a bunch of them to my class' Blackboard site for students to view at home and will show a couple on the most important people in class. Fantastic because they take up very little class time, but are focused on good content!