I have a client who needs the ability to show video ads before playing via AllVideos plugin.  Here is a post on the Joomla forums that I found:
forum.joomla.org/viewtopic.php?p=1434292

Is it possible to customize the AllVideos extension to include an advertisement before/after the video plays?  Maybe something similar to the Simple Image Gallery option where you can load a module position inside of the lightbox...

I've found something that might help with this - "Open Video Ads" - for the JW video player:
www.longtailvideo.com/support/open-video-ads/ova-for-jw-player-4