Look at this helpful thread. It lists projects that need help. Some of these need captioning (English soft subs copying the existing hard subs). I updated the list by clicking on each one of them. Most are restricted in my region but chances are that they are not for yours.
Of course the hard subs are not always very good, so they also need editing.
There is also another option There are variety shows spoken in English. Some of them hard-subbed, some not. The ones which don’t even have hard subs have to be soft-subbed for the hearing-impaired. But even those who are hard-subbed need soft subs if they are to be translated into other languages.
“Join Us Korea” is spoken in English, and hardsubbed.
This one doesn’t have any hard subs, so it is only for people who understand English very well (like you, who are a native English speaker)