There is no standard. It depends on the internet speed, size and quality. The three must be in balance.
If he is asking for WMV then that determines the big decision.
Start with a WMV prest then tweek it up and down till you reach the balance of qual vs file size that works. Test with a 10 second clip to save yourself test time. But a good quality under 15M for 2 minutes should not be difficult.
Main contributors to file size are Frame size, frame rate, Video BW.
For example; here is a 6 minute video that is 17M. On this one the guy cheated with frame rate to make the file smaller but the frame size bigger since there is little motion..
He may have the spot/size of the video predetermined for the site. So also ask him what size it needs to be in pixels. That will set one more variable for you.