Here's an example of what I directed the AI field to do and what it gave me for the first record.  We have over 1,000 entries here beyond this first one so it shouldn't have a problem finding ones to relate it to.  

Note: I think this is possible but it'd take a lot if credits

Hmm, I think the field can only grab data from that record?  To do what you need I think I'd try:
1. Create a new table called "Summaries" and link it to your main table
2. Link all the records from your main table to a single record in "Summaries"
3. In your main table, create a checkbox field called "Look for related content"
4. In your main table, create a formula field that concatenates the Segment Title and Descripton
5. In "Summaries", create:
  - Lookup field for the formula field mentioned in step 4
  - Lookup field for the formula field mentioned in step 4, but with a conditonal to only display if the "Look for related content" checkbox is marked

You should now have one field that displays all the Titles + Descriptions of the records in your main table, and a field that displays only the Title + Description of the content you're working on

And you can then feed the AI field these two fields, does that make sense?  I think this would be a super expensive thing to do though as Airtable AI credits are charged by the characters you're sending it, and if you're sending it 1000 titles + descriptions that'd be a lot of characters

From the docs: If you wanted to summarize a transcript from a 30-minute call that contained about 20,000 characters, it would require ten times as many credits, or 100 credits.

Assuming the credits thing is an issue I'd try just pasting all the titles + descriptions into Chat / Claude / program of your choice directly instead