I have the best solution, Google 'Freecorder' and download, automatically saves any video you watch on your computer, also record any sound that is played through your computer, by far the most useful thing I have ever downloaded. It has other features, but haven't personally looked into them.
It appears freecorder comes with some bad nasties.
New 8 core
Gigabyte GA-970A- D3 Full ATX Motherboard;AMD FX 8120 3.1Ghz; Corsair Vengeance 8GB Memory; 60GB SSD; 640GB WD; Geforce GT630 1GB Vid card; Windows 7 Professional 64 bit; Antec Three Hundred Mid tower
Built by Me!!
I've been using the Ant video downloader with Firefox for a few months. It works quite well with most streaming video sites incl Youtube. I do turn off the options to send downloading stats etc for privacy reasons. It also has a version for Internet Explorer but I've never tried it.