Yay ZIPs, but no RARs?

This app is simply the best one I ever used! Im a first time MMD user and this is a great experience!! But the downside is, when I download something that is a RAR file, it says that it is an unsupported file. This kinda made me mad. Most of the models and motions I want are in the RAR files. Is there a way to fix the problem, so that way I can use RAR and ZIP files together?

Nidi Love of Summer about MMDPlayer