I have this problem with Creator 2012 and Vista HP but found Corel fix 000013560 - Can not capture web video from Youtube by searching the Creator 2012 knowledge base with Video capture, I recall.
The URL is 611 characters so I copy from the Corel's page. "Resolution: pause the video at the beginning, then change the quality of the video from the default setting to any other setting (ex. 360p to 480p). Start playing the video again. The video should now show up in the Web Video window." It worked for me!