I have sudscribed to the documentation and I am trying to install plug_cbcaptcha_1_2_RC4.zip on my CB 1.2.1 installation but I am getting the following error:
Upload showPlugins - Upload Error
Failed to move uploaded file to /home/mysite/public_html/media/ directory.
I am trying the install from CB Plugin Manager Install Plugin
I found that it was a strange coincidence - the website had just gone "over quota" at that time and no uploads were allowed.
I had the quota increased and the plugin installed OK.