From the Digital Theatre website:
HD – High Definition HD offers greater picture quality and sharpness for the premium viewing experience. Our HD films are downloaded via the Digital Theatre Desktop player.
You will be able to view HD quality material if you have a compatible HD television or computer monitor. There is a short film giving an overview of how to connect your computer to a television in the How To section.
Of course the quality of the HD films is reflected in the larger file size which will result in slower download time than standard definition. This is dependant on your internet connection speed.
SD – Standard Definition Standard Definition is typically what you experience when viewing normal television channels. Our SD films are also downloaded via the Digital Theatre Desktop player. The quality is perfectly suited to watching the plays through a laptop or computer, and will also provide a good viewing experience when watched via a standard television. The files being smaller will download in less time than an HD film.
VOD – Video On Demand Video on demand offers the greatest convenience for getting access to the Digital Theatre productions. There are no downloads to install and you can begin watching the moment your purchase is complete. VOD is achieved using a technology known as ‘streaming’ (often the two terms are used interchangeably). Our systems automatically let you watch the film as many times as you like for 30 days from the first play.
Digital Theatre Desktop Player The Digital Theatre Desktop Player is our video player that is downloaded and installed for free on your computer and allows you to download and play our films. You can even test out our show trailers first before you purchase a production. Once downloaded the DT player sits on your desktop giving you quick access to DT and your library of productions. It works in a similar way to the other television over the web players.
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian