You can find these episodes on the ITVX official Love Island page in the UK or on Hulu in the US (often listed under the main season's episode list).

The specific content of "Unseen Bits #3" varies by season, as it covers the events of the of the show. Here is how you can find the guide for the specific version you are looking for:

Episode 20 serves as the third installment of unseen moments for this season.