A. First, you need to get the URL for the mp4 file. The file can be hosted anywhere and doesn't have to be on your site. If it is on your site and you uploaded it to the main folder the link will look like:
http://yourdomain.com/video.mp4
Once you have the URL you then go to edit the page and while editing the page for the video select the mp4 option. It will give you an input field where you can put the URL for the mp4 file. It is that simple.
The paragraph above assumes that your page is editable with an editable video section. If creating a page with the wizard you can specify where an editable video section should appear. If we are installing a page for you then you can ask us to install an editable video section at a specific location. By default when we install a page if we see a video we will install it as an editable video section. If you have an existing section that you want to be an editable video section you can edit it from the admin from /admin/editpages using the first edit link and then change the editable section to be an editable video section by editing it at the bottom of the page (if you also have editable html content in it then it needs to be separated into 2 separate editable sections, 1 for the video and 1 for the html).
Also, you can follow our instructions for page installation if adding a new page or editing an existing page without an editable section to add an editable video section. Doing this requires a good understanding of html.
At anytime you can open a support request to have us set things up the way you want it.