Hi:

On bludovedemo.biz/sinha/index.php/conditions-and-treatments if you scroll I have videos installed. How do I make them smaller?

Thanks.

Could someone please help on this?

get JCE pro and the video plug in
www.joomlacontenteditor.net/support/releases/changelog/media-manager. If you use JCE many of those plug ins come in handy and with a one year subscription, all are available

If you are using the responsive template, then the video will stretch to full width.
If you want to use certain dimension, you need to use another template.
You can also set a maximum width:

Paste this in your template's stylesheet.