This plugin routes all ads though adsbycb.com's own website with each load. Basicly http://adsbycb.com generates the links (code) and your server has to DOWNLOAD this info every time.
The issues with this are as fallows:
1. security - Because there code uses a blind include statement, you server will run anything they give you (See line 40 in file adsbycb.php)
2. Bandwidth, not only are you at the mercy of clickbank but also now adsbycb.com. Meaning that if adsbycb.com becomes swamped or just plainly goes down. So do your ads.
3. All Ads, and links are generated by adsbycb.com, so they have complete control over what is in your links. So they could and probably do include there own ID with in the links (think of it like a kick back).
So I state the fallowing, this code is unsafe and un-secure for anyones use.