Creating their own unique English subtitles to funny “foreign language” or silent movie scenes has been a fun language-learning activity done in many English Language Learner classrooms for years.
There are several tools that teachers have used for just that purpose, which you can find at The Best Places To Create Funny Subtitles For Silent Movies.
Caption Generator lets you do that for any video on YouTube, so ELLs and their teachers can now have even more choices.
However, you probably want to use it with caution. Some of the videos that have been captioned and viewable on the site may not be classroom appropriate. However, I assume (thought haven’t checked at my school computer) that those videos will be blocked by district content filters. I can’t be sure, though.