If you don't know about the TV safe area, read up!

In some video editors, the 16:9 safe area is indicated as the usual 10%. However, in some of our workflows, 16:9 gets cropped to 4:3 to give fuller images on some mobiles. Hence you certainly want the title safe area to be the usual 4:3 title safe area, contained within the 4:3 image.

Similar considerations apply for broadcast, see here:

• Test card for 16:9, http://www.bbc.co.uk/commissioning/tvbranding/picturesize.shtml
• Image showing positioning of copyright info, note 4:3 area contained in 16:9 image http://www.bbc.co.uk/commissioning/tvbranding/copyright_ind.shtml