Hi @kalincan, one thing that can be done is to add a custom code embed to the page, and then paste in the snippet you shared above and save the embed.
Next, create a text field in your collection and give that field a name that will easily identify the field as being the unique url you need to use for each post and save the collection. Edit your items with a unique url for each collection item.
From the looks of the code snippet, this should probably be this part:
After updating the embed, save and republish the site, and now each collection item having a url added to the collection, will get a different iframe content based on the url added to each individual item.