Choose a font size appropriate for your presentation context. A one-inch letter is readable from 10 feet, a two-inch letter is readable from 20 feet and a three-inch letter is readable from 30 feet. If you use a light background, use dark text. If you use a dark background, use light text. Select ‘PowerPoint Add-ins’ from the Manage drop down and click ‘Go…’ On the Add-ins dialog, click ‘Add New…’ . Navigate to the folder where the contents of the zip file was extracted and select ‘YouTubeVideo2k7.ppa’ and click on OK. You might be prompted with the macro virus warning.