That Deep Purple video is waaaay-cool! Love that classic line-up. I'm not sure I'd call that metal, though, definitely hard rock, but maybe not quite metal...
You're right about the lines being blurry, though, it's always tough to categorize musical acts in static categories. Some, like Purple and Zeppelin, straddle multiple genres. Led Zeppelin's Presence album, which I like intensely despite many fans panning it, sounds very metal and progressive to me at the same time. Rush's Cygnus X-1 is a very metal song.
About Tool, you cannot argue that Tool is not heavy. I can't think of one Tool song that doesn't rock hard. And I call them prog because they fit the profile, long instrumental passages, odd time signatures, disregard for radio-friendly format, and an emphasis on musicianship. In my opinion, of course.
YMMV
You're right about the lines being blurry, though, it's always tough to categorize musical acts in static categories. Some, like Purple and Zeppelin, straddle multiple genres. Led Zeppelin's Presence album, which I like intensely despite many fans panning it, sounds very metal and progressive to me at the same time. Rush's Cygnus X-1 is a very metal song.
About Tool, you cannot argue that Tool is not heavy. I can't think of one Tool song that doesn't rock hard. And I call them prog because they fit the profile, long instrumental passages, odd time signatures, disregard for radio-friendly format, and an emphasis on musicianship. In my opinion, of course.
YMMV