You might wonder if it's possible to tie a given Action item to some file you've shared with your client. For example: if the action item was to read an article or watch a video, could that be stored, embedded or hyperlinked within the Action item itself?
It is NOT possible to do with an Action item, but a Worksheet can be a great way to accomplish this.
You can add media (like videos or audio) easily to any Worksheet by clicking the "Add media" button, the video icon found 4 or 5 buttons in from the right:

This is great for putting videos or audio clips that are embeddable by CA right in the Worksheet itself. You can also link to an already-shared file (i.e., a link to an item you know will be in your client's Files area).
By doing this, you make that file readily accessible, AND you can give any instructions for reading that article or watching that video.
Like an Action, the same machinations of notifications, reminders, and marking it done apply to a Worksheet.
Better yet, you can even add some reflection questions that go beyond merely marking the task as "Done" (e.g., "What were your key takeaways from watching this video?").