Note: for courses, editing the expiration date and price of videos can only be done en masse at the Course level --- click On-Demand > select Course > choose dropdown > Edit.
For Collections, you can make this change at the individual level by clicking:
On-Demand > Your Library
Selecting the Collection (or Course) that contains the video
Note: to edit the whole collection's default price/exp date (and save some time), click Actions > Edit (top right) and skip to the last step.
To edit just the video, select the video. (bottom left)
Continuing with the video editing path, update expiration date or price, then click Apply Updates & you're done.
The Edit Collection page will allow you to:
edit the price/expiration date for all videos in the collection (use the 'override' toggle at the bottom); or
set the default price and expiration for only newly created videos (just the videos created going forward, leaving all others as is)