OpenCV installer will detect 'agree' checkboxes on screen and automatically uncheck them for you.

Take this with a grain of salt as it is speculation, but I'd be very surprised if there were not plans to vacate SF eventually.

But SourceForge does such a good job of packaging their installers with Value Added Software(tm)! Why would they want to leave? /s

The project is already on github if you want to build from source.