Great question. Creators who receive coins can cash them out for an actual monetary equivalent that is paid out through the same PayPal account currently used for the ad revenue program.
As to what exactly that equivalent is, it will vary because some people will use coins they purchased and some will use coins they earned. Some will also no doubt use a little of both.
On the back end, for coins that were purchased, we have to take out the Apple and Google "tax" that they charge us for using their sales platform.
For coins that people earn by watching video ads we do not have to take out any "tax".
So the actual value of the coins depend on which type are donated. But don't fret, the wizards on our dev team make sure all that is tracked and paid out accordingly.