this seems like they're monitoring our browsing history, in exchange for bitcoins...I could very easily be mistaken but seems risky
Every advertiser is using the url of the webpage you visit as one criteria among others to select the "right" ad to display.
So yes, of course we use the the url of the current webpage, but :
- we don't monitor browser history
- we do not need to archive the url
You can extract the source code from the plugin if you want to check what is really done, nothing is obfuscated.