iframe caused a publishing page's vertical scroll bar cut off

Hi,

I used a content editor webpart to add a video to my publishing page:

<iframe src="url of the video".../>

Unfortunately, some IE and firefox users have the vertical scroll bar of the page get cut off, as a result, they can only see up to a certain part of the page and can't use the vertical bar. But some of users' vertical scroll bars work perfectly fine.

Is there anything missing and how can this problem be fixed?

Please advice. Your help would be greatly appreciated.