So this is what worked for me, after signin:

(1) Load the video, put a place holder description in.

(2) Click your username in the top right corner, then click "Video Manager" is the list below.

(3) Find the video you'd like to add deeplinks to within the video's description.

(4) Under that video, click "Edit Info"

(5) Use the format "Text 00:00" - which is the same as the comments format and only support minutes and seconds, not hours, half-seconds, etc.

Note: It possible this works when loading the video, but already had the video loaded, and on other forums it said that didn't work anyway, so I didn't even bother to test it.

If it matters, the real format I used was "Text (00:00)" - which to me was easy to read and understand, especially after the time becomes hyperlinked and blue.