Last night's Grey's episode...

I almost never watch Grey's Anatomy but I use to back when it started (2005?). After catching it again this year I was surprised at how some of the cast has stuck around and to see this Justin guy still there I noticed that I haven't seen him in anything else on TV or in Film. Sure enough I looked up his IMDB page and his resume is 90% Grey's Anatomy with a few short films and video games? I wonder how he got his break in the first place.