Sizing imported video problems in Storyline

Hello all and thanks for looking at my post.  I am having difficulty resizing an imported video in Storyline.  I am attempting to increase the width and height of the video by dragging the tabs on the corner of the video box, which initially seems to work.  But when previewing the video, it does not retain the proportions.  

I am working at a 4:3 story size.  I have attempted to resize a MP4 using handbrake to 626x446px but after importing this file into storyline, the size changes to 720x405px.  I cannot seem to influence the size of this video import either by dragging the corner squares in storyline, or by changing the video output size in handbrake.  Any tips would be appreciated.  

Thanks in advance,

Joe