I would like to add a video to my sharepoint site. When I click edit > Insert, the Video and Audio tab is missing. How do I get this to work?
Assuming that this is in SharePoint 2010 you need to have publishing enabled to get this to work, doesn't work with Team Sites I think..
Support for Video and Audio is possible via Silverlight plugin. Make sure you can watch movies stored in Asset Libraries, by example, via the out-of-the-box experience(e.g. upload a WMV and while hovering click Play on the dialog which appears).
Don't use this function with other browsers (e.g. Firefox, Chrome) which do not support Silverlight, as many other components will be automatically disabled too.
Hope it helps, C:\Marius
SharePoint 2013 might require activation of Video and Rich Media site collection feature for this button to appear.
The feature adds the Site assets library app type to the site collection. Also, the Video and Audio button appears in rich text editors across the site collection (content editor webpart, pages, edit forms with rich multiline text).