(JokerWindow) Fix bogus timestamp when video is not opened with the doc

When the doc does not contain the path to the video, or when this
path is not valid, and when the video was opened later, the timeIn
was read from the videoEngine whereas it was never set. Fix that
by reordering the calls.
Merge pull request #274 from tlecomte/tlFixVideoTimeIn

Timestamp issue when video is not opened with the doc