I hadn't heard of these insects until earlier today when a friend about 100 miles south of me reported his first encounter with this problem. Searching the Internet shows they have been found in many cities in California, more in SoCal than NorCal, so I'm surprised I hadn't heard of them before. Also, I only found one mention of them in passing at F4F (from a member who had had no experience with them), which is also surprising. This insect is large and loud and my friend says they are scary despite experience with such things as dealing with skunks and raccoons many times.
This video is sort of funny with the calm voice the lady uses, seems she's got pretty used to them.