World 7 - Level 3
Start moving immediately and push the steel boxes along yellow paths. As soon as the final boulder for the first bridge starts rolling you need to start running along the green path - if you were too slow with the boxes the passage will be blocked by a boulder. Run along the green path collecting three of the Rainbow coins. Then wait until the boulders complete the second bridge. Once the second bridge is complete run over it and prepare to release the conveyor button (blue circle). Do so just before the next boulder arrives - roughly when it is at the blue "X". You will now have made a path for the Rainbow Spirit to collect the remaining coins. There is another conveyor button under a box behind the level exit - you can use this one to collect remaining bonus coins.