Hi Chris,
I don't know about Macs, so I would have a look at the main DNN forums and ask around for any experienced Mac developers. - As long as you can get ASP.NET and SQL Server running you should have no problems.
Regarding the videos, all of the videos are in Flash format, as this provides the best quality for creating video tutorials.
You can download Flash from:
http://www.macromedia.com/shockwave...sion=Shockand you can see what version of flash you have installed using:
http://www.macromedia.com/software/flash/about/I would recommend that you upgrade to the latest Flash version if you are having any problems playing the videos.
Thanks,