This is the right site for you. It's the way how you can get videos from Youtube easy! Downloading your favorite Paris Hilton music video or funny ad commercial, sketch or whatever you like from those sites, save it on your computer to prevent from deleting or to trasfer to your iPhone or any other mobile device to watch it everywhere you walk.
If for some reason downloaded movie doesn't work on your computer, you should try K-lite codec pack with codecs able to play flv files in your Windows Media Player on your PC. As alternative you can search for dedicated free FLV player in search engine. There are plenty of them. For example:
Or you prefer to convert downloaded file to something more common like avi, mpg or wmv to play it on mobile players. If you are owner of iPod, you need to convert them to mp4 format. Some free converters are listed below: