Some Buckeyes do roar and like Pathfinders, I have heard other breeds make a similar noise. The unusual, bold noises are common of the large Asiatic breeds which are part of the Buckeye ancestry.
The best Buckeye "roars" are loud, deep, low growls with some duration (can be longer than a crow). When first hearing a good roar you will wonder, "what was that?" There are varying degrees of the roar as well. My best roarers rear back & up like they are crowing when they do it (and like a crow, it gets better as the rooster gets older). It is difficult to predict when they are going to roar so is the reason nobody has captured it & uploaded it for the internet. They seem to do it when alarmed or excited (one time I had a Buckeye cockerel I could hear roaring repeatedly outside so I ran out to see why he was so alarmed-- he had a mouse he was holding down with his foot & excited at letting up his foot and re-catching it, he would roar loudly). Some of mine never or very rarely roar (so all Buckeye males don't make the noise). The Buckeye hens sometimes "squawk" very loudly when protesting something.
My Buckeye males also make a "crying noise" or a "whining," when I have them in isolation & separated, like they are saying, "I'm so sad, poor me, pity me, please let me out."
[I've often wondered why it has been called a "dinosaur roar" since nobody has ever heard a dinosaur noise (& who coined that term?).]