How do I insert a video into a pre-determined box?

I'm creating a series of Storyline modules that contain multiple videos (one per slide), plus a menu, quiz, etc. 

I'm using roughly the same template each time, so I've been simply opening up the last file I used, deleting the old videos, and inserting new ones, then making changes to the other slides/menus/quizzes, etc. 

It dawns on me that I'm probably not working very efficiently -- I keep having to resize and move the videos that I insert (they're 1040 px wide, and I need them to be 1000 px wide .. then I move them over slightly each time). 

Is there a way to create a box that is the right size and location, and then to insert a video INTO that box?  I've played with this awhile and can't figure it out ... haven't found another post with this question, either. 

Thanks in advance for the assistance.