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@jeremydebose You probably used the defaults command to alter the behavior of Safari.

Open Terminal and enter this command:
defaults write com.apple.Safari IncludeInternalDebugMenu 1

This will expose Safari's "Debug" menu. Under that debug menu, go to Media Flags, and then check if Disallow Inline Video is checked. This will stop videos from automatically playing when a page loads. Uncheck it and see if autoplay returns.