Simply logging in with my user name and private posting key works for me but I have found that D.Tube works inconsistently. Sometimes my videos appear to upload but the process never really finished or I get various errors when I try to publish. It seems pretty random. Sometimes it works fine, sometimes not (and all the videos I have attempted to upload so far are in the same format and are less than 10 minutes long).
I know that her videos tend to be kind of long, but I don't think she can even log in from what I gathered from our brief conversation.
The only thing I can think of is to make sure she is clicking the Show Private Key button before copying the key. Otherwise she'll by copying the wrong thing.
I thought of that too and told her a little bit ago... Thanks!