In many cases, it can be 20-30 minutes between the time you cue up a DVD to play a segment and the time in the service when you need to play it. Unfortunately, most DVD players will have gone into some form of sleep mode that can require an uncomfortable pause before it spins back up, loads the buffer, and begins to play. Or if you have it in a PC, sometimes you can't recover at all if the PC went to sleep or it takes an eternity to spin up, causing the audience to get restless and the murmur of congregational talk rises . If you have a Mac, it still can take a few seconds before the DVD spins up again and is ready to play. But at least with a Mac, you get a decent DVD player that is designed to work with the system, not a cheap third-party add-on commonly found in PC's that I haven't found to be as stable in a dynamic environment.
In the past, what I have often done is used Handbrake (a free download) to rip a chapter off a DVD into a QuickTime file and then use QuickTime's Pro features to trip off what I don't need. I would then drop this QuickTime file into ProPresenter onto a slide so I could flow right into it right after a song or announcement, making a very smooth transition. The problem with this is that not all DVD's can be ripped, you need time to do this (I figure 2.5 minutes of ripping for every minute of video), and there is some quality loss, although most people would probably never notice it.
With the newest version of ProPresenter, there is an option to prevent DVD spin down. So you can cue up a DVD in ProPresenter's DVD player, play your songs and smoothly transition in and out of the DVD clip.
So why not use a standard DVD player? Well, to make sure your DVD player is ready to go, you need a separate monitor and a multiple input/output switch so that you can preview it offline and then bring it up on the main screen. Hopefully, in the rush to keep things moving, you don't mess up the switch. Second, it adds another layer of devices, cables, etc.
The other issue is one of using multiple screens. Some PC's have trouble keeping the dual screen settings when it loses the video output. So when you switch to another device and return to the PC, it has to re-initialize the dual screen setting.
In larger churches, this may not be an issue but in small churches where you have a lone ranger at the media station, this is much more critical. The Mac operating system has the ability to recognize most projectors by name and keep those settings if you use a switchbox between sources. And if there is a reason that you need to turn on/off dual screen support, that can be done with a single mouse click. No jumping into menus three levels deep and a bunch of mouse clicks to set resolution and dual monitor support as on a PC.
With a tool such as ProPresenter, you can deliver a seamless approach to moving between service elements.