If you use Mozilla Firefox you can download 'Download Helper' which is a fantastic free plugin, it will download almost all video's from You Tube and other similar sites as flv files, you will need to convert into a format Magix will recognise before importing or you can buy 'Download Helper' for a small fee and it will do the conversions for you.  It also works with Internet Explorer but was originally written for Firefox.  I have not found Magix products reliable enought for streaming video's, its a bit hit and miss whether the end product will turn out right, the settings seem to change of their own accord so I use 'Applian Director' then import into Magix for editing.  There are other products out there both free and to buy for downloading You Tube video's, another good one is a product of AShampoo's but for me and I recommend 'Download Helper'.