The first clip is the song "Summer Lovin'" from 1978's Grease. The big change here, however, is that it is now in stop-motion lego animation. I've provided the original clip as well so you can see just how accurate the animation is to it's original.
This clip is called "Mellow Brick Road (Wizard of Oz Remix)". In addition to the postmodern animation, the creators have taken all original music and spoken audio clips to create a soundtrack to the story that everyone already knows so well. Similar to Grease, it now gets a modern and fresh treatment which breathes new life into something that has been around for over 70 years.