Your movie has multiple audio tracks, and one of them is the narration track (Visually Impaired track, for blind people). MC is selecting the correct audio track based on your language preference, but apparently your Roku is selecting the wrong track (or just picking the first track which happens to be that one). Assuming your TV is using DLNA for streaming, MC has no way of controlling this, it's up to the TV/Roku settings.
Possible solutions:
- You should have a menu or button on the remote to select the audio track. Maybe you've turned on some accessibility setting.
- You can re-rip your movie excluding the unwanted audio tracks, leave only the main one
- You can use MKVToolNix or some other tool to rework the already ripped movie and remove the unwanted track, or change the track order/preference so that the Roku picks the correct one.