Ian of Forgotten Weapons really does get to play with all the cool toys. In the first video he reviews the General Election M134 minigun in 7.62×51. He gives an in-depth explanation of how they work and especially how they feed the ammunition.
Ian has produced a second, shorter, follow-on video showing the M134 minigun firing in slow motion at both 2,500 and 5,000 frames per second. It is amazing how hypnotic watching a minigun can be. That is, so long as you aren’t the target of it!