What should I know before I can understand this topic?
Follow
Do you want to understand that specific video, or the topic generally?
Study "Jim Crow" laws and also the Voting Rights Act of 1965.
https://en.wikipedia.org/wiki/Jim_Crow_laws
The ones who want more restrictions and ID requirements, claim that it is to reduce voter impersonation.
https://en.wikipedia.org/wiki/Voter_impersonation_(United_States)
@Pat
Better both. They are related.