download manager

i use eagleget or FDM for downloading files from internet but recently both have started to download html files instead of the real files . What is the problem and what should i do to solve it????

I want to download videos from YouTube but i just know about the Internet download manager, I use this as 30 days trial but it ask key after that. I have no money to buy it, could you please suggest me the download manager which allow me to download all YouTube videos form internet but it must...