Yes it is. The box under the video will display a 'progress bar' when you first click 'upload to YouTube'. This bar will stay on screen until the video is uploaded while you stay on that screen. If you navigate away from that screen however, and return before the video is uploaded, then the green 'upload to YouTube' box will re-appear. The video will still be uploading to YouTube in the background. You do not need to click on the upload button again.
(we're working on making the 'progress bar' reappear when you navigate away and return to that screen).