Let's be honest - watching most music DVDs is about as exciting as watching extra slow-drying paint dry extra slowly. Almost all of them are recorded gigs with a few brainless extras and, as such, are strictly fan-only affairs. Even then one wonders whether said fans really sit in their living rooms pretending they are lodged in a temporary concert epicentre while they watch people on screen actually enjoying themselves.
If the second disc in this two DVD set was all there was to The Lesser Lights Of Heaven, then I might well be sat here eulogising about the loss of three hours of my life. Don't get me wrong - Zao are a mighty, mighty band but with the musical truculence they deal in, it's even more important to witness them live rather than starting a one-man moshpit chez Bansal. And even diehards might struggle to persevere with the sounds-like-it-was-recorded-in-a-U-Bend mix of the second show here...
No, The Lesser Lights Of Heaven is groundbreaking for the jewels contained on disc one - a three-and-a-half hour documentary directed by Zao's manager and respected rock critic Ryan Downey, which leaves absolutely no stone, nay pebble, unturned in its pursuit of wringing out everything there is to know about the history of Zao.
At this point you may be wondering why anyone but a fanatic would want to sit through over 200 minutes of interviews about a band they've hardly heard of. You might have a point - you do kind of need to care about Zao - but for anyone with a passing interest in extreme music, metalcore or the collision between rock music and spiritual faith, this is a fascinating insight into a band who spawned a genre, never got the credit they deserved and whose tale has more plot twists, personality politics and subterfuge than an episode of 24.
Perhaps director Downey's greatest achievement here is facilitating all band members past and present (in Zao's case that's about 20!) to display an honesty that is as brutal as the music that Zao purveys.
There is no coyness about the fact that Zao were borne out of a church youth group; that the line-ups who recorded All Else Failed and The Splinter Shards Of Separation were zealously evangelical, particularly at gigs; but that Zao were soon rejected by many members of their churches for creating the "demonic" sounds of Where Blood And Fire Bring Rest and Liberate Te Ex Inferis - seminal, trailblazing albums that are inadvertently responsible for the current plethora of metalcore bands who blend thrash metal savagery with open wound, hardcore lyricism.
Nor is there the remotest holding back by the band members when they confess that 2002's Parade Of Chaos album and the 2003 re-recording of All Else Failed were done purely for financial reasons and that they are pretty ashamed of the latter, both for the concept and the execution.
To make matters spicier, the two strongest characters emerge in the utterly antithetical form of current vocalist Dan Weyandt and former drummer Jesse Smith. To some Weyandt may seem aggressive in appearance (tattoos up to his neck; earlobe rings the size of ashtrays) but he is softly-spoken, thoughtful and emotive. The section where he talks about his upbringing; the death of his step-brother and various friends; his nervous breakdown; and the fact that his faith is the only reason he's alive today is genuinely tear-jerking.
Smith, on the other hand, is at turns hero and villain, an embodiment of contradiction. He persevered in keeping the Zao flame burning through years of being overlooked; yet there is no doubt that Zao's inability to retain band members was not unrelated to his presence in the band, while he is still remarkably unpenitent about Zao's shambolic on-stage break-up in 2001, when he was too drunk to play.
Having said that, Smith does better than many would at trying not to be bitter about Zao's relative commercial success since he parted ways with Dan Weyandt, Scott Mellinger and Russ Cogdell (the implied "core" of Zao) and they released the stunning Funeral Of God album.
Except that this being Zao, there is an unspoken twist to the tale for, since this DVD was made, Cogdell has also left. But then Zao's story is at times a tragedy as Greek as their band-name. With a new album on the way, produced - curiously - by Steve Albini, let's hope it has a happy ending.