According to this trending video's description, Adam Starr lost his leg to cancer in 2009 and this is footage of his first day back in a gymnastics gym. The clip has been rising quickly on social bookmarking website Reddit since it was first posted by the young man earlier today.
The number of videos Starr has posted suggest that he's not just been a solid athlete for a while -- as evidenced by the clips of his diving skills -- but also a talented musician. Check out some of his acoustic covers here and here.
He also posted a video two years ago of his first steps with the prosthetic c-leg, which makes for an interesting counterpoint to the video above: