This well-positioned and nicely shot video by mtarver captures a grand slam homer (the caption on the video page says a three-run homer, but it's definitely a grand) by the Indians against the Devil Rays in a spring training game. If you want more up-to-date (and major-league) footage, check out the YouTube submissions of someone who goes by the screen name of Andrea 1282. S/he has clips from the Indians' home opener, which featured a home-team grand slam.