Exclude multiple custom post types from search

This is because elseif doesn’t work the way you think it does. You’re trying to use it in a way that’s closer to a switch statement or multiple if statement`

This:

    if (post_type_exists('videos')) {
        // exclude from search results
        $wp_post_types['videos']->exclude_from_search = true;
    } elseif (post_type_exists('coordinator')) {
        // exclude from search results
        $wp_post_types['coordinator']->exclude_from_search = true;
    }

Is the same as this:

    if (post_type_exists('videos')) { // if videos exists
        // exclude from search results
        $wp_post_types['videos']->exclude_from_search = true;
    } else { // if it does not exist
        if (post_type_exists('coordinator')) {
            // exclude from search results
            $wp_post_types['coordinator']->exclude_from_search = true;
        }
    }

else if just shortens things so that it’s more readable and takes less time to type. It’s called syntactic sugar.

If you want to check multiple things in a row, then you should use multiple if statements in a row:

if ( condition1 is true ) {
    // do a thing
}

if ( condition2 is true ) {
    // do a thing
}