This is a feature from Screenconnect and it works pretty good.
Basically the text in your host keyboard is typed out on the remote session. Why not just copy and paste? Well, consoles, (thru SSH for example), devices with different form factors and OS, etc. might not support copy and paste and this method works perfectly on a universal scale.
It would be really useful.
This would be quite useful - I use lastpass for password management, and it would be nifty to be able to copy and paste into login dialogs.
It would be great to allow as well with Keepass to allow the UserID and password to be passed along to TeamViewer and typed in instead of paste. Paste doesn't work at Windows login prompt.