Note that many websites have their own advertising, unrelated to adware.
The Onflow player calls back to Onflow's servers when an advert is played, with a player ID. This allows tracking in a similar way to 'third party cookies'.
Currently, it comes secretly with an entire range of products and is secretly installed.
Onflow claims that the software will no longer be bundled with other applications, and that the next version will be able to warn users before installing updates.
The 'Add/Remove Programs' option seems to work fairly well. It leaves an 'uninstall onflow' item behind in your Program Files directory, but this is easy to delete.