If they are protected and can't be downloaded with right-click and save as, then you could try going on "view source" and searching for the link. It may start with mms:// but could also begin with http://, it's something that you will have to play about with. It could also finish with .asx .asf .wmv .wml or many others. Just try and search for those in the page source and you should eventually come across the link.
The problem is they cant be ripped from the site but you can find the videos stored in your temp internet folder as a FLV file so if you can find a player that can play this file type then that should do it.
this will play the FLV file and its free so heres what to do,
first watch the whole film on your tube so its downloaded into your temp file then goto control panel and click on internet options then click settings then click view files then search for the flv file you want and move it to another file such as my videos or your desktop then download the flv player from here