Have you ever come across that dreadful JW player that you can't find a way to download streamed videos?
I know one can dig enough in this area but I will try to enlighten some of that here.
First of all, download rtmdump and Chrome as your browser. let's hope you are using Chrome as your browser. Right click anywhere in the page, select "Inspect element" and a new pop-up window will appear that lets you look at the code. Find the part (Chrome puts a blue-ish canvas when you select a part) and open all the nodes ( click on the arrows) to find exactly the part where the video is located in your page. You must reach up to a point where the last node of your video will look like this:
