i can not find a problem with the content plugin in jD 2.5.x. See my fast test below.
Fresh installed with the last version 2.5.21.
The notation in the content plugin itself states this.
The content plugin was at first written for the 3.2 series and then only tested with the 2.5 series.
As modifications was not required, we have also not changed the notification. That it's all.
Please describe more detailed your problem (exactly error messages or screenshots).
Also your versions...