Hansen breaks down several scenarios and ways in which clickjacking can be used, so I strongly suggest reading his full post on his blog, as I really wouldn't do his explanation justice.
Adobe has posted an advisory to address concerns about clickjacking and they have stated they are preparing a critical a patch for Flash Player. In the meantime, Adobe advises IT administrators to change the AVHardware Disable value in client mms.cfg files from 0 to 1 to disable client Flash Player camera and microphone interactions. It also recommended users go to the Global Privacy Settings panel of Adobe Flash Player Settings Manager and select the "Always deny" button.
For a video demonstration of a clickjacking attack against Flash checkout researcher Guy Aharonovsky's blog post "Malicious camera spying using ClickJacking". He does note that Adobe has fixed this issue but it is still interesting to watch and gives you a good idea of how clickjacking works.