ADA History - In Their Own Words: Part One. - Administration for Community Living, Office of Civil Rights (This has three parts but includes video reflections from those involved in crafting the law. The videos are fairly short.)
While ostensibly focused on military families, this eight-minute video helps in understanding how the different laws (ADA, 504, IDEA, interact when providing services in special education.
This six and a half minute video from the US Department of Labor explains how the Rehabilitation Act of 1973 (and updates) work.
ADA
This two and a quarter minute video is a short, animated film that explains aspects of the ADA
This twelve-minute video tells a bit about the history of the ADA as well as its strengths and shortcomings
A ten-and-a-half minute video explains, in good detail, how the ADA and employment interact. There is a short passage about drug use and alcohol use which might be of interest, too.
State Law
Mental Illness is a covered classification. Sadly, this disability is often overlooked, and manifests needs differently than do physical disabilities. This six-minute video describes the Trueblood suit and settlement. In recent times, you likely have heard about some of the changes this suit precipitated.