Downloading videos using iTunes, how can I back them up? I subscribed to these podcasts which are actually vidoes.

I can see that iTunes downloads them locally to my computer, but I am not sure of the location of where they are downloaded.

I want to transfer them to a CD or my other computer, how can I do this?
Will iTunes possibly delete these after a while if I don't view them?
By default the files iTunes uses are located in : 

~/Music/iTunes/iTunes Music


iTunes does not delete podcast files by it self. You have to do it manually.