You don't need tapers tickets.. DMB has one of the most liberal and generous taping policies out there right now...
You can tape from your seat anywhere in the venue. If you're in the centered section, you're restricted to head-height because of the cameras in the middle. However, the Dave & Friends tour may have a different video setup, but generally this is the rule.
The preferred way to get a good tape is stack taping since it's a mono mix. Get a good seat near the stack, run high, and you're golden.
Tapers seats used to be availible via the Warehouse (fan club), but I haven't seen that option for a while.. they put you right behind the board (which was, in shed shows, a stellar view and sound, imho)...
Also, esp. for the indoor shows, dont' raise your stand until the band comes onstage.. The only times I've had people complain about my stand was the indoor shows when I was high up before the lights went down, and they can actually see the half inch of piping that they claim is blocking their view... once the show starts noone usually cares.
The taping policy is located under the "Legal" portion of their website..
Enjoy!