The Html5 Video Player WordPress plugin before 2.5.19 does not sanitise and escape some of its player settings, which combined with missing capability checks around the plugin could allow any authenticated users, such as low as subscribers to perform Stored Cross-Site Scripting attacks against high privilege users like admins
https://wpscan.com/vulnerability/759b3866-c619-42cc-94a8-0af6d199cc81