Easton, don't worry - it's your customers.
I handle customer service for MaxCash sites and I have both Mac and PC (but prefer my Mac hands down!) I have no trouble with .wmvs on our sites on the Mac... I think your customer's problem is his browser. Tell him to try using IE for Mac (available at
http://www.mactopia.com) or Firefox (
http://www.mozilla.org/products/firefox/) to browse the site. Safari is just not good for porn sites. I would also put this in your help pages as it will avoid many emails for you.
As for a G4 without a mouse... I think he meant he only has a one-button mouse. You can use third party mice (like Microsoft's Intellimouse) and have the right click work to give you alt menus, but if you have the standard one button Mac mouse (the only sucky part Apple refuses to let go of) it's a pain to get to said alt menus.
If you have any more questions or ever need stuff tested on a Mac, LMK... traycedactyl on AIM (sorry - I rarely use ICQ)