MXF will work though it won't always play them directly; go to the file types page in preferences and make sure it is enabled. For the ones that won't play, use Clip->Maker 422 Proxies to make proxies that should play. You can do that in batch. For RED... we'd like to support RED files but just have not done the development yet. It's a big job for a relatively small number of users. Would love to find some funding for it though as I have some RED clips myself that I would love to get organized.