Here's some info on them:
Flash cookies are a new way of tracing your movement and storing a lot more information about you than with normal cookies. One major disadvantage of flash cookies is that you can’t locate them in your browser. They are not shown in the list of cookies that you can see when you take a look at the cookies that are currently saved in your web browser. Normal HTTP cookies can’t save more than 4 Kilobyte of data while Flash cookies can save up to 100 Kilobyte. If you want to try out how they work you could do the following.
Go to Youtube, increase or decrease the volume of the videos and delete all cookies afterwards. You will notice that the volume level is still at the same level when you close your browser and open it again. This is done with so called Local Shared Objects, better known as Flash cookies. The main question is of course how a computer can be checked for Flash cookies and how it would be possible to delete those cookies again.
This is actually a very tricky thing. I was searching for a way to check them on my computer but could not find it. After reading some information on the Adobe Flash Player website I was able to realize that the only possibility to check them was to open a page on the Adobe site which would show them.
Rest here with charts..I'm going to try this solution and see what it does for me