Even though a video or reading may not give specific information about a person or an event, you can often use what you see, hear, or read to infer that information. In this case, you know something about facing difficult problems, and you can apply that knowledge to understanding Julian's character. Julian's actions in response to racism lead us to infer that he had the character trait of perseverance, to keep going no matter what challenges he faced.
In the video you just watched, how did Percy Julian demonstrate perseverance in the face of racism?