"How about downloading cube / looks dangerous.. "
well the cube's source code is free software (although its some media files are not) and you can check it for any "dangerous" code, and if you do find some just remove it. (If you can't do so, you can still ask someone else.) However I have glanced the code and found no "dangerous" stuff
Also as a BU member (Rick) is also working on Cube, you can just trust it