YFrog API no longer supports public/private option?

Question

I'm tring to use YFrog's API to upload a picture. The documentation is as follows

http://yfrog.com/api/upload

Use this method if you only want to upload a photo or video to yfrog.

Request fields

(post data should be formatted as multipart/form-data)
media - Binary image or video data; either media or url parameter is required
url - URL of image or video; either media or url parameter is required
username (required) - Twitter username
password (required) - Twitter password
tags (optional) - comma-separated list of tags. (tags can also include geo tags)
public (optional) - Public/private marker of your video/picture. yes means public (default), no means private key - DeveloperKey.

However whenever I include the public in my POST parameter, it returns incorrect username/password. But if I don't include the public parameter, everything works fine. What's wrong?

Also, side question, what is the rate limit when uploading to yfrog?