k, if you use safari this is what you need to do
step 1 go th the video you want on youtube
step 2, while it is downloading (its easier to find when its dloading) go to Window>Activity wen u are in the activity, you look for the file size on the right that is still downloading and usualy the biggest, somtimes its hard to dond id u have fast internet
step 3 click on it it should start to download
step 4 you convert it to mpg. Isquint is the best for macs...really easy
step 5 watch