The USA conducted over 200 tests with nuclear weapons and technology in the mid-1900s, and you can bet that they captured a LOT of video footage while gathering data and researching all of that power they were trying to learn how to control. For a long time, those videos were classified and locked away from almost everyone.
Recently, over 700 of those videos have been reviewed and declassified by the government. You can read more about this project on theverge.com.
Here are a few videos to get you started...
Around 60 of those videos are available on YouTube already. You can view an extensive playlist of those videos right here.