Captivate 9 - Publish to Video - Inconsistent size between slide dimensions in Captivate and dimensions of MP4 video

• I have a slide project that is set to size 1280 x 720 
• I want to keep these dimensions so that it syncs up with another video (the same size)
• I publish my project as a video and the resulting MP4 does not maintain the same size

What could I be doing wrong?