Like Kim said, welcome to the wonderful world of Macs
I too am a Mac user and it took some time for me to figure out everything with this site on a Mac since most of the help was for PCs. We have created a Mac guide that you can check out
here. Below are just a few little tips I discovered during my year and a half on this site and with a Mac:
1. I like Safari better than Firefox. I had more problems on Firefox so I switched to Safari and barely have had problems.
2. I did go through a time where neither Safari or Firefox worked very well. Instead I started watching the videos directly in RealPlayer. Here's how to do that:
--Open up RealPlayer
--Go File-->Open Location-->enter the url for the site viptv.net
--You should then be taken to the vip homepage and can use RealPlayer as you would any other browser
Hopefully one of these solutions will work, but if not, let us know what you did and what is still not working so we can find some other way to get you watching again!