Yes, MC for Mac plays *almost* any kind of video available. The organization generally starts under the Video tree on the left and can be customized to your heart's content.
Let me start with the kinds of video that MC for Mac won't play: ISOs of DVDs and BDs. DVD and BD file structures that contain the low level files that come directly from these optical discs. Essentially any "straight copies" of DVD or BD won't play in MC for Mac (unless I'm mistaken).
However, MC will play pretty much anything else, including MKVs made from DVD or BD. MKV files can contain 100% of the audio and video data (and quality!) from the original DVD or BD, so this IS a full quality option. Of course AVIs, MP4s, and other types of video will play as well, whether they are ripped from optical disc or from other sources.
Why do your videos show up under documents? They really shouldn't. Occasionally I see this happen on my system, but it's usually when MC is trying to import a partial video file: One that is not complete.
More importantly, how to fix it? No problem. Just highlight the file or files in question, the open the Tag Action Window with Edit > Tag. You'll now see the TAW on the left where you can set all of the tags for those files. The tags you want to work with right now are [Media Type] and [Media Sub Type]. If you don't see those displayed, click on the gear icon at the upper left of the TAW and select an option to display more tags.
Once you get those tags displayed, edit the [Media Type] to be Video. Next, set the [Media Sub Type] to Movie or TV Show, or whatever category these files should be under.
After you make these changes, the files should then appear in the correct views under Video. You can change these views, or make new ones. I made new ones for Movies, TV Shows, Educational, and Music Videos as my video collection grew.
All of the power of MC is available for video files, so you can really organize them exactly as you want to see them.
Good luck!
Brian.
