Try two separate searches:
As a student at Green River College, you automatically have access to online library resources at King County Library System.
To search for documentaries on YouTube:
1. in the search box, type: [name of your case] documentary. Example: Tinker vs. Des Moines documentary
2. Note that you will still need to determine if the results are actual documentaries. Looking at the length, quality, and depth of the film as well as which organization produced the film can help you determine if it is an actual publicly-distributed documentary versus just an opinion piece or non-professionally-produced video clip.
Not documentaries, but interesting talks: