Accuracy with alternate picking is something that will come. Don't get discouraged if your practice doesn't pay off right away. The best thing to work on accuracy is do some chromatic runs with a metronome. Start off at a beat that you can do pretty easily and cleanly... then speed it up gradually. This works for me but I don't claim to be a speed demon and I rarely go off on self-indulgent shred solos....... I'm not sure about those videos. I almost guarantee you will learn something by watching them... Michaelangelo is a shred machine.