Phillip Worrall

I have recorded a song through Garageband, and uploaded it to video pad with intentions of putting a video of me singing to the external audio track. I record the video whilst singing to the external audio, so they're synchronized and lined up and should be perfect, or at least in theory. The videos appear juddery once they are uploaded to videopad. Being very new to videopad and editing in general I wonder what I am doing wrong can someone help many thanks and kind regards Phillip