I wanted to compare streaming a ripped DVD from my Plex server to my new Stream+ against my Roku 3.
Streaming a DVD ripped into a 480i MKV file by MakeMKV to the Roku requires the Plex server to transcode the file to MP4 as it streams. In comparison,the Stream+ allows it to be streamed via "Direct Play" so the Plex server has very little load on it while it is streamed.
http://screenshot.ontrapedia.com/public/fhagan/e9c25374-e6f5-41b4-aa5e-eda72f9fec6b1521825052.png
Roku only supports MP4 MPEG4 files and while MKV is an MPEG4 file, its the MKV container that Roku doesn't support. This is the main reason why I don't even bother with Roku, they don't support a wide array of codecs and seems unlikely they ever will.
DVDs use VOB for the container, which are basically MPEG2 files, which I think Roku does support. But you convert that to MKV and suddenly it wont play it. So yeah, you need to transcode those files for Roku to play it.
Personally, I would get a Raspberry Pi and image onto a MicroSD card, either OpenELEC or LibreELEC and use that as a back up (it will play any file, no transcoding needed) if you grow tired of always having to convert files just so Roku can play it.
My Mi Box direct plays almost everything I have. H264. H265. MPEG. AVI. It only transcodes the audio because Plex can't figure out what I have since I'm using the SPDIF connection so everything is 2ch stereo mode.
Streaming a DVD ripped into a 480i MKV file
Everyone has ignored that you are streaming Interlaced video content. Unless any media player can deinterlace that properly then you are going to get dull, half motion video output.
$149? I wonder how it compares to a $69 Mi Box. Was probably a better buy when the promo price was just $99.