There are several content downloaders like You_tube_downloader and many others. However i don't wnat something which is specific to one site or another. is there something like Real_player_for_windows which is capable of downoading_any flash content which it comes across any_website on the internet. I need something generic and which holds true for every website not just one or two
I think, FlareGet would be an ideal choice for you. It is available for free in Ubuntu Software Center
But the free version in Ubuntu software center does not support "Browser integration", you need to pay $10 to get browser integration plugin. I guess without browser integration, download manager won't make sense.
So here is the workaround to get Broeser integration for Firefox. I have tested it on Firefox 18 and it works like a charm.
Just right click any downloadable link and choose FlareGet.
I love Firefox so this is enough for me. Something similar can be worked out for Chrome.