There's a dance video about a boy's journey practicing dancing, and there's a part where the guy is dancing and walking with a backpack on his back, and the music in the background is I believe?

Based on the information you provided, the dance video is probably The Jazz Dancer.

The video focuses on a boy who grows up with a love and dedication to dance and eventually becomes a great jazz dancer through his tireless efforts. In the video, the scene of the boy dancing with a backpack on his back and the background music match what you have described. The background music is an English song called "I Believe" by Korean songwriter Eom Seung-min.

Please note that due to the large number of similarly-themed dance videos on video sharing platforms, you will need to verify the accuracy of my answer.