Is it possible to show a trailer video to provide an impression of what viewers would subscribe to?

Yes, you can upload trailer videos to show viewers what they will have access to before signing up. There are basically 2 options on how to show trailer videos in your apps:

1. Using the Trailer Feature: Assign a trailer video to each of your videos. A "Play Trailer" button will appear next to the "Play" button for the video. Trailer videos are independent from a subscription, meaning they can be watched with our without a paid subscription.

More about the Trailer Feature:

https://help.lightcast.com/video-on-demand#trailers

Watch how you can assign a trailer to a video:

2. Dedicate one VOD Channel for previews, trailers, marketing videos etc. which promote your subscription product and provide an impression of what viewers would subscribe to. We recommend to add the "Free Preview" VOD Channel on the very top of your Apps using the App Builder: https://help.lightcast.com/video-guides#app-builder