Video auto-resizing too big

Hello,

When I put a video on my WordPress page the video width is automatically sized to fit the page. I try changing the html to make the video dimensions smaller, but my html width setting always gets ignored by the WordPress template. It adjusts to my height setting, but not width.

How do I fix this? Unfortunately, I can’t mess with the code for all the WordPress pages on this site (I only control this one page).

http://scienceonline.com/scienceonlineteen-2/

Thank you!
Stacy