Plex is easy for some but I find it hard to use and excessively cumbersome and flaky to use.
The easiest of the media channels to get to work is Chaneru. This link
is to the Chaneru beta as it is the easiest to get working. It is free as long as it is beta.
You download the server. Copy it out of the zip file to where you want it to run from. (I use C:\Chaneru) Then run the server.
On the computer on the server's screen click options and then set your options the way you want.
Set your Server Name to whatever you want.
The IP and port should be preset to the computer's IP and 8010 as the port. I would suggest changing the port to something a bit less common to avoid conflicts. (I use 9091)
[This can be done as many times as needed to get the server to serve all video directories]
Next use the browse button in the Title Bar section to choose the directory that your videos are in. Then name it whatever you want. Then click add.
Then click update.
That is all there is to getting the server set to serve your videos. You can go back anytime and add more directories.
Then log onto your Roku account and then on the screen you downloaded the server from and click the line that starts with "Add Chaneru."
Then follow the instructions to get it added to your channel list. (It is not yet in the channel store)
Lastly, on your Roku enter and exit the channel store and Chaneru will be in your lineup.
Note: If you have the new interface with the channels in a 3 channel wide grid then you need to go to settings and "Check for update" to get the channel added right away. It will add automatically if you wait overnight but I have never liked waiting.
Once you have the channel entering it should bring you an entry for the server you installed and then you can select it and locate your movies and play them.
Chaneru can be set to transcode movies on the fly but it is much better if they are in one of the compatible formats like mp4. See this link for more info about encoding. viewtopic.php?f=66&t=36754
If you need to transcode Chaneru uses VLC so that will need to be installed on your computer.
NOTE: This version of Chaneru is DLNA capable for many DLNA servers but the experience while using the Chaneru server is, I believe, better than any of the DLNA servers that I have tried.