Definition: to think something over, probably very contemplatively and very seriously
Play this video at the same time as this one. You may have to adjust the volumes a bit for the right balance; you can also tinker by starting the music or clip at different points, so it ebbs and flows at the right points. There are many more soundtracks and scenes to mix and match, so explore some more!
Selected music from bensound.com/royalty-free-music.