When you upload a video the 'Add to Kwidget' box is already ticked for you and (if you choose to leave it ticked) the video is automatically added to your kwidget.  If you have already uploaded a video which you originally chose not to add to your kwidget and now wish to do so please follow the following... 

Go to your 'Engine Room' on your 'Home' page and select Video > Manage Playlist > Edit My Playlist.  Look for the Video you wish to add to your Kwidget  and then click on the 'Add To Kwidget' link next to the chosen Video. 

The Video is now added to your Kwidget. 

NOTE: You may also Remove a Video from your Kwidget on this page by clicking the link 'Remove from Kwidget' next to the Video you wish to remove.