That is absolutely incorrect: the box has been designed as a receiver.
All multimedia functionality is a bonus.
Please don't forget that all video decoding is done in hardware (hence the almost zero CPU load during playback), so playback functionality depends on the codecs used in your media files.
In general converting any media to MKV using the H264 codec is your best option. Then playback will equal TS-playback.
Further more it is advisable to install the plugin (audio-apple-lossless-alac) available on our feeds.
For full multimedia playback you need a multimedia player.