Problem With Multi Server

I'm not sure what happened with my multi-server. I thought that all videos were suppose to be uploaded to the newest server added to the list. However, out of the last four videos uploaded to my site, three were uploaded to the latest server, but one was uploaded to the original server. I'm not sure why that happened. Any ideas?

"If FTP server is down or login details are not correct, video will get uploaded to local folder."

Check documentation here: http://docs.buyscripts.in/Multi_Server_Support

But my question is: how to check when a server is full? Any way to pur like a size limit for each new server added?