Open the WeTime app, close the timer if needed and navigate to the second tab to view the list of your recordings.
Once you have selected the one you would like to export to youtube, press on it to view the full preview.
Use the actions button on the top right to view the list of available actions for this recording.
Press "Save Video" in order to export this video to your photos album.
Once this is completed exit the app and go into your Photos.
Select the video you have just exported and press the actions icon at the bottom left.
Press the YouTube icon and fill in the title and description for your video, then press "Publish".