Roku itself has to be able to support the video codecs, can't be done via the app. Requires licensing costs to support certain formats. Roku would have to pay Microsoft for supporting AVI container. Typically old XviD based videos will use that AVI container rather than MP4. XviD is becoming a dead format anyways.
Router - ASUS RT-AC68U
ISP - TWC - 50 Mbps/5 Mbps