Adding Administrators to a Subdomain

I have added a subdomain (
off of my main site (

I added an Admin to the subdomain so this Admin can add all the contents and media to the site. However, she is getting errors such as "cheatin huh?" and other things like not being able to embed videos.

I do not want to make her a super admin or an admin to the main site, since she is hired to work on the subdomain only and I don't want anything altered, even accidentally on the main site.

Is there anything I can do to fix her errors?