I just noticed the Dailymotion players had stopped working for a reason known only to them, so I had to change one code from X to Y in about 70 posts. There's no option built into this forum to do that, but this line of code run in the "SQL" tab of phpmyadmin did the trick.
I'm posting it here in case I lose the link. Obviously the "smf_messages" variable will depend on your database.
UPDATE smf_messages set body = REPLACE(body, 'OLD THING', 'NEW THING')