Having spent the best part of two days trying to work out why I couldn't FTP into my Foscam HD Cameras, it turns out that Foscam have changed the way the firmware works.
Unfortunately this is not very Apple Mac friendly and definitely not friendly to my Foscam HD plugin which will throw errors when it can't FTP to the camera.
With the latest firmware, the camera's FTP is now turned off when the camera is re-booted. It can only be turned on by logging onto the camera via a web browser (Safari), going to Settings > Record > SD Card Management and ticking the SD Card Management. The gotcha, is that on Safari the button is disabled and greyed out.
There is a long thread about it on the Foscam Community Support forum here: http://community.foscam.com/forum.php?mod=viewthread&tid=1139
Firefox and Chrome don't have the necessary Foscam plugin on the Apple Mac, so the only way I have found is to use windows (via a VM) and use IE to log onto the camera and click the button.
Another alternative/ work-around, is to change the camera to FTP to a FTP server (maybe on your Apple Mac running under Apple server). This way the images will be downloaded onto your Apple Mac and not stored on the camera. The good news is that the Foscam HD plugin supports this method of working.
This is a catch-22 situation. You need to update to the latest firmware to keep everything secure but if you do it stops working!