Ah, I had the same problem with my first batch.. I found the seeds at the local Asian mall.There's coriander, but it's very finely ground. Don't nobody got any whole ones, so I'm looking at online or going to the hippy shop for the next batch.
I have to emphasize that getting the actual seeds and roasting in the pan them is the key ingredient to the smokey flavor its supposed to have!
Biltong has a smokey, meaty flavor, if you dont have the smokey part, its like bbq chicken withouth the bbq sauce!