So I decided that this was a good oppurtunity to learn some Python and write a new FlickR plug-in for Plex. FlickR uses OAuth 1.0a to authenticate users against their API, so I found an existing oauth.py file that handled all of the signature complexity. I quickly discovered that the Plex plug-in's run in a sandbox environment, so I was restricted in which libraries I could import, this made things a bit akward but not impossible.
The Plug-In requires your FlickR username and password, after which it will display a list of your PhotoSet's to choose from. Here's a screenshot of the Channel:
As I mentioned you'll need to enter your FlickR username and password into the FlickR Channel Settings:
The source code for the Plug-in is available on GitHub here. Please raise any questions or suggestions on the GitHub page.
To install the plug-in on your Plex Media Server, locate the following folder:
\\<YourServer>\Plex\Library\Application Support\Plex Media Server\Plug-ins
I have a Synology Disk Station where Plex is installed as a Package, so the location might be different depending on which flavour of Plex you have installed.
Create a new sub folder called FlickR.bundle and copy the Contents folder from the GitHub repository into it. You might need to reboot or restart the Plex server afterwards.
If it doesn't work please have a look for the log in the following folder:
\\<YourServer>\Plex\Library\Application Support\Plex Media Server\Logs\PMS Plugin Logs
There should be a file called com.plexapp.plugins.flickr in which hopefully will be a clue as to the problem.