1.Play the video fully or atleast buffer it fully 2.Click Start >all programs>accessories>system tools>disk clean up 3.Select your default windows drive which is usually c 4.select Temp internet files and click View files 5.Make sure u have checked that hidden folders and system files are visible 6.3 or4 folders will be there , enter each and of them and change view settings to details (Ignore any warnings that may come) 7.Look for a file of size larger than 1 mb or so (usually 1 minute videos will be 1 mb and for each mb it may be 1 mb more) 8. copy them to another directory and rename them to something.flv or .mp4
If u use opera then play file fully
then open my computer>documents and settings>Local
settings>Application data>opera>opera>your profile>cahce
4 change view to details and find the largest file .It is your video
For both to work donot close the browser after the video is buffered and both hidden files and system files must be visible. This method is usfull for nearly all sites.