How to remove source files after conversion?

Hi Folks,

I have 2 directories.
Dir1 contains only flv files. (source directory of conversion program flv2mpg)
Dir2 contains only mpg files. (output directory of conversion program flv2mpg)

Now I want to delete all flv files from Dir1 when they are converted ie when a file with similar name but different extension exists in Dir2.

If you need more info please ask,

Thanks,

Dweep