I have not tried this with my mac, but on a Windows PC when I try to transfer an AVI file I get a message that the file type is not supported by the TF (when doing so via USB connected to the PC). I attempted to change the file name to .mp4 and it did not work. I changed it to a .mp3 and it transferred fine, then I changed it back to .avi after and it worked fine. You could try this. http://www.transformerforums.com/for...t-your-pc.html
Also, do the files in question have any DRM (digital rights management)? If so, this can make them pretty useless to the TF.
You could also set up an FTP or SMB file sharing on your mac and use ES File Explorer to transfer the files over the network. Here is a guide (the instructions for setting up a Mac FTP server are a bit later in the thread).