So I would like to start using a video for our announcements instead of PowerPoint. There is only one thing preventing me from doing this, and that is EW defaults to playing videos without looping/repeating them. I noticed there is a repeat/loop button when the video goes live and is playing, which is nice, but this setting is not saved within the schedule. So when I set the schedule up on Friday, there is no way for me to set the video to loop so that it repeats for our projectionists on Sunday morning. I suppose I could add "press the loop button" to their list of things to do Sunday morning, but I'm pretty certain it will be missed/overlooked/forgotten more than I would like.

It would be nice if I could set a video to loop, and this setting would be retained in the schedule, so that it loops accordingly the next time the schedule is opened.

We have this on our list of things to do. I think you'll be able to edit properties and set it to loop in the video properties.
For now, you can create a new presentation.
Then click on the media button and drag the video onto the first slide in the slide column. This will make it a background and will make it loop automatically.