I Ace and collect the vast majority of the currently accessible single-player Goodies in the "The Collector's Lair" level. (I missed two Goodies that can be annoying to get, but I'll just get them on a revisit.)
Despite the multiple annoying parts in this level, I really like "The Collector's Lair". It makes great use of Pistons and a moving environment, and it's not something you see often in platforming games. It's not heavy on art like some other levels, but the technical and creative aspects of the gameplay make it great nonetheless.
I found it amusing that Devante and Uncle Jalapeño were "freed", yet they managed to get stuck by the physics of their fall.
When going down the second tunnel with electrified hazards, I swear I just barely missed getting electrocuted by one of the hazards attached to a piston. Electrified items (especially in those tunnels) have a tendency to kill you even if the smallest portion of your feet touch them, so I was amazed I was lucky enough to get a near miss.
Also, yes, I did alter the Pod. I kept it plain and at its default status for the vast majority of this walkthrough, but I added some simple yet nice decorations now. The Pod will likely indirectly crop up in future videos of LittleBIGPlanet's DLC and in LittleBIGPlanet 2.
Revisit: No revisit is mandatory, but I separated the Cooperative Challenge area from the collection of single-player Prize Bubbles to make it easier on myself.
I quickly revisit the "The Collector's Lair" level to pick up two Goodies that I missed in my initial recorded playthrough since those Prize Bubbles can be a little tricky to get. Then, I cover the Cooperative Challenge (and its exclusive Goodies) for this level.
This level contains the final Cooperative Challenge in the Story Mode of this game, and it happens to be a very simple task that requires four players. (In actuality, this "Challenge" can easily be completed by just three players if the uppermost player makes a strong jump after three Buttons are held down. Keep that in mind in case you have difficulty rounding up a total of four.)
Special thanks also goes to the random online players featured in this video. The Neon Wireframe male with the green top hat goes by the PSN ID of baba451. The other male with a top hat (who eventually switches to using the lovely Chinese Dragon Mask) goes by the display name of Jaden. I am unaware of his PSN ID as he was playing LAN with baba451. Finally, the male with the dark colored hat goes by the PSN ID of Uxmal_The_Alux.
By the way, this is the penultimate video. At this point, the only thing that remains is to defeat the final boss known as The Collector. This walkthrough has shown you how to get every Medal, every Gift and every last Prize Bubble in the Story Mode of LittleBIGPlanet, and it is soon coming to an end.