Killer Ziller: Belly Dance Finger Cymbals
This DVD by Michelle Joyce claims to be a complete introduction to zills, from the very basics to dancing with finger cymbals.
It's well presented and clearly explained, so in my book it fulfils that promise - but a word of caution: some find the beginning drills are just too fast for them to follow.
So, if you're not already familiar with the basic belly dancing rhythms, this DVD might be too challenging for you. If that's the case, the answer isn't to find a better zills DVD - the answer is to study the rhythms first. A short drumming course is one of the best ways of doing that - I recommend Uncle Mafufo's Basic Rhythms DVD. You don't even need a drum, I just used the table!
For beyond beginners/intermediates who are comfortable with rhythms and are about to embark on playing the sagats, Killer Ziller is a good choice in my view.
I still think Tobias Roberson's Finger Cymbals DVD is the best buy, because it has so much material you'll keep coming back to it for years. However, if you want a DVD that also gives you some dance practice with zills, you'll need Killer Ziller.