The only way I know of being able to delete a user without deleting videos is to reassign the videos to another user (from mySQL or phpMyAdmin) and then delete the account. This would preserve the videos that the user uploaded. I hope this is changed in 2.7.

As for video swipper, the problem isn't that any video that gets swiped shows up under one user as much as vShare requires that a video be associated with a user. That is the reason why video swiper needs a user account (if you do not have a user, you cannot have a video show up on the site). This is something else that I hope is changed in 2.7.