You are definitely a big fan of Slash and I do get the sense that the only thing you wish to practice is Slash stuff. It's not that I'm knocking that but that in order to play like him, you need the tools he has. To do that, you want to know all the blues licks and also being exposed to the people he listened to.
If you watch the video through the eyes of having known those things, what that guy plays is not that terrifying. It would take practice to get it down. If it is improvisation, you definitely want those blues licks because knowing them makes you understand how to do that.