This first one is a pin that I found on Pinterest of Indiana Jones that I always enjoyed watching how it was set up. The camera follows the marble with classic Indiana Jones movies scenes in the background made out of legos. The loop follows the music made when the marble hits each of the slots to make the melody of Indiana Jones’ main theme. The loop placement is well hidden due to how the marble remains at a constant pace at the beginning and end of the looped sequence. Due to how the music and marble placement are done, the loop feels continuous with no break from the loop.
The second one is an Minecraft animation that has a spinning cube at its center. Within the cube reflects the journey of a normal Minecraft player to complete the game from the overworld, to the nether, to the stronghold, to the end, then jumping back into the overworld. The music and sound effects help blend in the loop by making sure each part has its own segment of music and sound effects that fades in and out at the beginning and end of the cycle.
The last one is an animation tutorial about how movement of falling down to see how much movement is needed for the animation to feel more real than fake or rigid. They show how to keep the loops hidden within animation to keep those who are watching from knowing where the animation begins and where it ends.