Up until early this year, I used to be able to use tools like Opera’s ExtendTube and Firefox’s DownloadHelper to download videos hosted on an artists’ Vevo channel on YouTube.
It used to be that Youtube videos were downloaded as FLV files which could just be stored and played over. Youtube doesn’t like this and they changed it so that the file is encrypted and can only be decrypted for a short time. Now if you go to a Youtube page, pause the video and try to restart it after some time (hours) it will not play and will display an error message and you have to refresh the page all over again.
So now you cannot just “save” a video because that will not work, now a program or addon needs to render it on the spot and convert it to something plain which is not encrypted of limited in any way. So, there is a conversion going on.
I have even done successfully a screen capture using Virtualdub. It is somewhat complicated but you can capture anything.
Lets you save the video as an mp4 file. You don’t need to download any program. Just copy and paste the URL of the YouTube video into their download box, and download the video.