I'm not aware of any widescreen release of Howard. (I could kick myself now for passing on a 35mm print that was on ebay a couple years back! Like I had any way to run it!) When it hit pay per view, the "Duckumetary" teaser and music video were in heavy rotation on the preview channels, so somebody must have taped them back then. I just found one trailer on Utube.
There are actually two versions of the music video. The first version is edited to avoid showing what Howard looks like before the movie was released, and the second has Howie in all his ducky glory.

"He's our leader." George Lucas, Howard the Duck teaser trailer.

EDIT: dcfcfan beat me to it!