Often customers prefer to preview content to feel reassured about the purchase, so it's handy for them when you have some of your videos available for free. When creating collections, you might want to make an introduction video to be played at the beginning of each collection that will be available for free just to let your customers know what to expect. It differs from a trailer since it gives you a chance to show the quality of your content in a meaningful way.
To make a video available for free, navigate to Content > Collections and select the collection you want to change, then click Edit. Under the Playlist tab, you can toggle Available for free for the video(s) you want to leave free.
On the collection page, the free video will appear without the lock icon, and anyone will be able to play the video without logging in or purchasing the collection.