Not too many Drosera have visable tentacle motion, so you will have to do a time delay method of observation to appreciate the activity: check the plant hourly, and observe what is going on closely. Some "faster" species include glanduligera, burmanii, sessilifolia, and good old capensis. I watched my capensis alba ensnare a blue bottle wasp yesterday, quite large it was too! I would never have thought it capable. Within an hour, the leaf had rolled around the wasp.