Beware the blurring tools. At least some of them can be reversed. You're probably better off cutting out the section and replacing it with something else.
The difference between the plate being visible IRL and on the Internet is that only a few thousand people will see it IRL, and they're all local to you. On the Internet, it's visible to 7 billion people, and if one of them decides to do something illegal with the info, you'll probably not be able to identify or prosecute him.