The YouTube videos widget lets you quickly and easily display your most recent YouTube videos in your blog's sidebar.
Because the thumbnail image does not have TITLE or ALT attribute, the whole website is failing validation. Having TITLE or ALT attribute in IMG tag is a must and basics of HTML.
Once its fixed, rating will go to 5/5.
Can you make a html tags to use this plugin in post or page? For example <YouTubeWidget username="" type="" number=""></YouTubeWidget>